Pneumatic Tire

ABSTRACT

A pneumatic tire includes protrusion portions formed on at least one tire side portion of tire side portions located on both sides in a width direction, projecting from a tire side surface that is a surface of the tire side portion, and extending along the tire side surface, the protrusion portions having an angle α within a range of no less than 6% and no more than 50% of an angle of one round in a circumferential direction, the angle α being relative and in the circumferential direction between two protrusion portion end position lines that respectively extend in a radial direction through different end portions of both end portions in an extending direction of the protrusion portions, and the tire side portion having a thickness at a tire maximum width position within a range of no less than 2 mm and no more than 9 mm.

TECHNICAL FIELD

The present technology relates to a pneumatic tire.

BACKGROUND ART

In recent years, technologies have been proposed in which convex finsare provided on a tire side portion in order to improve fuel economy byheat dissipation and aerodynamic effects. For example, in Japan PatentNos. 5147324 and 5849572, Japan Unexamined Patent Publication Nos.2013-018474 and 2015-212117, and International Patent Publication No. WO2016/181940, by providing convex fins on the tire side portion, and bydevising the position, shape, and the like of the fins, a temperaturereduction effect (Japan Patent No. 5147324), an improvement in fueleconomy performance (Japan Patent No. 5849572), an improvement inaerodynamic performance (Japan Unexamined Patent Publication No.2013-18474), an improvement in running performance of the vehicle (JapanUnexamined Patent Publication No. 2015-212117), and a reduction of airresistance (International Patent Publication No. WO 2016/181940) arepossible.

One effect of providing fins on the tire side portion is improved fueleconomy performance as described in Japan Patent No. 5849572. In otherwords, by providing the fins on the tire side portion, turbulent flow isgenerated when the tire is rotating, an increase in air resistance issuppressed, and rolling resistance is reduced, whereby fuel economyperformance may be improved. However, in order to obtain the effect ofimproved fuel economy performance by providing fins more effectively,increasing the size of the fins increases the mass of the fins andincreases the mass of the entire tire. In this case, even though finsare provided, the effect of improving fuel economy performance may bedifficult to obtain.

On the other hand, when the size of the fins is reduced in order tosuppress an increase in mass, it becomes difficult to sufficientlyobtain an aerodynamic effect, making it difficult to generate turbulentflow. And therefore, this also makes it difficult to obtain the effectof improving fuel economy performance. Moreover, when the thickness ofthe tire side portion is made thinner in order to suppress an increasein mass while providing large fins for the purpose of improving fueleconomy performance, scratch resistance will be easily deteriorated. Assuch, it has become very difficult to effectively improve fuel economyperformance without diminishing scratch resistance.

SUMMARY

The present technology provides a pneumatic tire that can provide bothscratch resistance and fuel economy performance in a compatible manner.

A pneumatic tire includes a plurality of protrusion portions formed onat least one tire side portion of tire side portions located on bothsides in a tire width direction, the protrusion portions projecting froma tire side surface that is a surface of the tire side portion andextending along the tire side surface, the protrusion portions having anangle α within a range of no less than 6% and no more than 50% of anangle of one round in a tire circumferential direction, the angle αbeing relative and in the tire circumferential direction between twoprotrusion portion end position lines that respectively extend in a tireradial direction through different end portions of both end portions inan extending direction of the protrusion portions, and the tire sideportion having a thickness at a tire maximum width position within arange of no less than 2 mm and no more than 9 mm.

In the pneumatic tire described above, the protrusion portionspreferably have a distance Dmax and a distance Dmin, the distance Dmaxbeing a distance in a tire radial direction between a tire outerdiameter portion and an innermost portion of the protrusion portions inthe tire radial direction, the distance Dmin being a distance in thetire radial direction between the tire outer diameter portion and anoutermost portion of the protrusion portions in the tire radialdirection, and a relationship between the distance Dmax and the distanceDmin is preferably within a range of 1.2≤(Dmax/Dmin)≤3.5.

In the pneumatic tire described above, the distance Dmax is preferablywithin a range of no less than 0.30 and no more than 0.70 times a tirecross-sectional height.

In the pneumatic tire described above, the protrusion portions arepreferably formed across the tire maximum width position on the tireside surface in the tire radial direction.

In the pneumatic tire described above, in the protrusion portions, aposition of a portion in the tire radial direction where the height fromthe tire side surface is highest, is preferably included within a rangeof no less than 0.40 and no more than 0.60 times the tirecross-sectional height.

In the pneumatic tire described above, in the protrusion portions, aposition of a maximum width portion in the tire radial direction ispreferably included within a range of no less than 0.40 and no more than0.60 times the tire cross-sectional height.

In the pneumatic tire described above, the protrusion portionspreferably include at least one bent portion at a position where adirection in which the protrusion portions extend changes.

In the pneumatic tire described above, the protrusion portions include aplurality of extending portions defined by the bent portion, and a firstextending portion, which is the extending portion having a longestlength among the plurality of extending portions, has an angle β withina range of 0.60≤(β/a)≤0.90 with respect to the angle α, the angle βbeing relative and in the tire circumferential direction between twofirst extending portion end position lines that respectively extend inthe tire radial direction through different end portions of both endportions in the extending direction of the first extending portion.

In the pneumatic tire described above, the protrusion portionspreferably have an angle θ1, the angle θ1 being formed between a centerline in a width direction of the first extending portion and a centerline in a width direction of a second extending portion, the secondextending portion being the extending portion continuous from the firstextending portion via the bend portion, and the angle θ1 is preferablywithin a range of 90°≤θ1≤170°.

In the pneumatic tire described above, the plurality of extendingportions of the plurality of protrusion portions preferably have a samedirection of inclination in the tire radial direction with respect tothe tire circumferential direction.

In the pneumatic tire described above, when a vehicle moves forward, thepneumatic tire is preferably mounted on the vehicle in such a way thatthe pneumatic tire rotates about a rotation direction that isdesignated, and the first extending portion is preferably inclined in adirection from an inner side to an outer side in the tire radialdirection with respect to the tire circumferential direction while goingfrom a leading side to a trailing side in the rotation direction.

In the pneumatic tire described above, the protrusion portionspreferably include an overlapping portion that is a portion wheredifferent protrusion portions overlap in the tire circumferentialdirection.

In the pneumatic tire described above, the protrusion portionspreferably have an angle γ within a range of 0.05≤(γ/α)≤0.30 withrespect to the angle α, the angle γ being in the tire circumferentialdirection in a range where the overlapping portion extends in the tirecircumferential direction.

In the pneumatic tire described above, two of the protrusion portionsoverlapping each other in the overlapping portion preferably have amaximum distance Pmax and a minimum distance Pmin in a tire radialdirection between the overlapping portions, and a relationship betweenthe maximum distance Pmax and the minimum distance Pmin is preferablywithin a range of 1.0≤(Pmax/Pmin)≤2.0.

In the pneumatic tire described above, the minimum distance Pmin ispreferably within a range of 0.15≤(Pmin/SH)≤0.30 with respect to a tirecross-sectional height SH.

In the pneumatic tire described above, the protrusion portions overlapin the overlapping portion, and one or more of the protrusion portionsare preferably arranged at any position on a tire circumference.

In the pneumatic tire described above, a sum of the angles α of theprotrusion portions formed on one tire side portion is preferably withina range of no less than 105% and no more than 200% of the angle of oneround in the tire circumferential direction.

In the pneumatic tire described above, the protrusion portions arepreferably formed on one tire side portion within a range of no lessthan two protrusion portions and no more than sixteen protrusionportions.

The pneumatic tire according the present technology is able to achievethe effects of providing both scratch resistance and fuel economyperformance in a compatible manner.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a tire meridian cross-sectional view illustrating a mainportion of a pneumatic tire according to an embodiment.

FIG. 2 is a detailed view of a tire side portion outside the vehiclemounting direction in the pneumatic tire illustrated in FIG. 1.

FIG. 3 is a view in the direction of arrow A-A in FIG. 2.

FIG. 4 is a detailed view of portion B of FIG. 3.

FIG. 5 is a detailed view of portion B of FIG. 3, and is an explanatorydiagram of the position at which a protrusion portion is disposed.

FIG. 6 is a detailed view of portion B of FIG. 3, and is an explanatorydiagram of the position where the protrusion portion is disposed withrespect to an arrangement possible region.

FIG. 7 is a detailed view of the protrusion portion illustrated in FIG.5.

FIG. 8 is an explanatory diagram of the angle θ1 formed by the centerline of a first extending portion and the center line of a secondextending portion illustrated in FIG. 7.

FIG. 9 is an explanatory diagram of a comparison of the inclination ofan extending portion illustrated in FIG. 7.

FIG. 10A is a cross-sectional view of D1-D1 of FIG. 7.

FIG. 10B is a cross-sectional view of D2-D2 of FIG. 7.

FIG. 10C is a cross-sectional view of D3-D3 of FIG. 7.

FIG. 11 is an explanatory diagram of the position of the maximum widthportion Wm of the protrusion portion.

FIG. 12 is a schematic diagram of the protrusion portion illustrated inFIG. 7 as viewed in the E-E direction.

FIG. 13 is an explanatory diagram of substantial parallelism between afirst extending portion and a third extending portion.

FIG. 14 is an explanatory diagram of an overlapping portion betweenadjacent protrusion portions.

FIG. 15 is a detailed view of the overlapping portion illustrated inFIG. 14.

FIG. 16 is a modified example of a pneumatic tire according to anembodiment, and is an explanatory diagram of a case where there is onebend portion in the protrusion portion.

FIG. 17 is a modified example of a pneumatic tire according to anembodiment, and is an explanatory diagram of a case where there arethree bend portions in the protrusion portion.

FIG. 18 is a modified example of a pneumatic tire according to anembodiment, and is an explanatory diagram of a case in which the firstextending portion is positioned further toward the inner side in thetire radial direction than the second extending portion.

FIG. 19 is a modified example of a pneumatic tire according to anembodiment, and is an explanatory diagram of an average extendingportion height of a plurality of extending portions of a protrusionportion including four bend portions.

FIG. 20 is a modified example of a pneumatic tire according to anembodiment, and is an explanatory diagram of a case in which thecross-sectional shape of the protrusion portion is formed into arectangular shape having a lateral length.

FIG. 21 is a modified example of a pneumatic tire according to anembodiment, and is an explanatory diagram of a case in which thecross-sectional shape of the protrusion portion is formed into atrapezoidal shape.

FIG. 22 is a modified example of a pneumatic tire according to anembodiment, and is an explanatory diagram of a case in which thecross-sectional shape of the protrusion portion is formed into atriangular shape.

FIG. 23 is a modified example of a pneumatic tire according to anembodiment, and is an explanatory diagram of a case in which arcportions are formed at the base portion of the protrusion portion.

FIGS. 24A to 24F are tables listing the results of performance tests ofpneumatic tires.

DETAILED DESCRIPTION

Pneumatic tires according to embodiments of the present technology aredescribed in detail below with reference to the drawings. However, thepresent technology is not limited by the embodiment. Constituents of thefollowing embodiments include elements that are essentially identical orthat can be substituted or easily conceived of by a person skilled inthe art.

EMBODIMENTS

In the following description, the tire radial direction refers to adirection orthogonal to the rotation axis (not illustrated) of apneumatic tire 1, the inner side in the tire radial direction refers tothe side facing the rotation axis in the tire radial direction, and theouter side in the tire radial direction refers to the side away from therotation axis in the tire radial direction. Moreover, the tirecircumferential direction refers to the circumferential direction withthe rotation axis as the central axis. Additionally, the tire widthdirection refers to a direction parallel with the rotation axis, theinner side in the tire width direction refers to a side toward the tireequatorial plane (tire equator line) CL in the tire width direction, andthe outer side in the tire width direction refers to a side away fromthe tire equatorial plane CL in the tire width direction. The tireequatorial plane CL is a plane that is orthogonal to the rotation axisof the pneumatic tire 1 and passes through the center of the tire widthof the pneumatic tire 1, and in the tire equatorial plane CL, the centerline in the tire width direction, which is the center position of thepneumatic tire 1 in the tire width direction, coincides with theposition in the tire width direction. The tire width is the width in thetire width direction between the outermost portions in the tire widthdirection excluding the protrusion portion 30 (see FIG. 1) describedlater, or in other words, is the distance between the portions farthestfrom the tire equatorial plane CL excluding the protrusion portion 30 inthe tire width direction. “Tire equator line” refers to the line in thetire circumferential direction of the pneumatic tire 1 that lies on thetire equatorial plane CL. In the following description, a tire meridiancross-section refers to a section in which the tire is cut along a planeincluding the tire rotation axis.

FIG. 1 is a tire meridian cross-sectional view illustrating a mainportion of a pneumatic tire 1 according to an embodiment. The pneumatictire 1 illustrated in FIG. 1 has a specified mounting direction withrespect to the vehicle, or in other words, the direction when mounted onthe vehicle is specified. In other words, in the pneumatic tire 1illustrated in FIG. 1, the side facing the inner side of the vehiclewhen mounted on the vehicle is the inner side in the vehicle mountingdirection, and the side facing the outer side of the vehicle whenmounted on the vehicle is the outer side in the vehicle mountingdirection. It should be noted that designation of the inner side in thevehicle mounting direction and the outer side in the vehicle mountingdirection are not limited to the case of being mounted on the vehicle.For example, in a case of being mounted on the rim, the directions ofthe rim with respect to the inner side and the outer side of the vehicleare determined, so in a case where the pneumatic tire 1 is mounted on arim, the directions with respect to the inner side in the vehiclemounting direction and the outer side in the vehicle mounting directionare specified in the tire width direction. The pneumatic tire 1 includesa mounting direction indicator portion (not illustrated) that indicatesthe mounting direction with respect to a vehicle. The mounting directionindicator portion, for example, is constituted by a mark orrecesses/protrusions provided on the sidewall portion 4 of the tire. Forexample, Economic Commission for Europe Regulation 30 (ECE R30) requiresthat a mounting direction indicator portion be provided on the sidewallportion 4 on the vehicle outer side when the tire is mounted on avehicle. The pneumatic tire 1 according to the present embodiment ismainly used for passenger vehicles.

Moreover, the pneumatic tire 1 according to the present embodiment is apneumatic tire 1 in which the rotation direction when mounted on avehicle is designated, or in other words, the pneumatic tire 1 ismounted on a vehicle so as to rotate in a designated rotation directionaround a rotation axis when the vehicle moves forward. The pneumatictire 1 also has a rotation direction indicator portion (not illustrated)that indicates the rotation direction. The rotation direction indicatorportion, for example, is constituted by a mark or recesses/protrusionsprovided on the sidewall portion 4 of the tire.

In the following description, the leading side in the tire rotationdirection is the rotation direction side when the pneumatic tire 1 isrotated in the designated direction, in the case where the pneumatictire 1 is mounted on a vehicle and is rotated in a designated directionwhen traveling, this is the side that first comes into contact with theroad surface or moves away from the road surface first. In addition, thetrailing side in the tire rotation direction is the opposite side to therotation direction when the pneumatic tire 1 is rotated in thedesignated direction, and in a case where the pneumatic tire 1 ismounted on a vehicle and is rotated in a specified direction whentraveling, this is the side that comes in contact with the road surfaceafter the portion that is located on the leading side, or that separatesfrom the road surface after the portion that is located on the leadingside.

The pneumatic tire 1 according to this embodiment includes a treadportion 2, shoulder portions 3 on both sides of the tread portion 2, andsidewall portions 4 and bead portions 5 that are sequentially continuousfrom each shoulder portion 3. The pneumatic tire 1 also includes acarcass layer 6, a belt layer 7, a belt reinforcing layer 8, and aninner liner 9.

When viewed in a tire meridian cross-section, the tread portion 2 isformed in an annular shape extending in the tire circumferentialdirection at the outermost portion in the tire radial direction, and isexposed on the outermost side in the tire radial direction of thepneumatic tire 1, with the outer peripheral surface thereof becoming thecontour of the pneumatic tire 1. The outer circumferential surface ofthe tread portion 2 is formed as a ground contact surface 10 that is asurface that can come into contact with a road surface mainly duringtraveling, and a plurality of grooves such as circumferential grooves 16extending in the tire circumferential direction and lug grooves (notillustrated) extending in the tire width direction are formed on thecontact surface 10. Furthermore, the tread portion 2 includes a treadrubber 18 that is a rubber composition. The tread rubber 18 may includea plurality of rubber compositions with different physical propertieslayered in the tire radial direction.

The shoulder portions 3 are portions of the tread portion 2 located onboth outer sides in the tire width direction. Additionally, the sidewallportion 4 is located on the inner side in the tire radial direction ofthe shoulder portion 3, and a pair of the sidewall portions 4 aredisposed on both sides in the tire lateral direction. That is, the pairof sidewall portions 4 are disposed on both sides of the tread portion 2in the tire width direction, or in other words, the sidewall portions 4are disposed at two locations on both sides of the pneumatic tire 1 inthe tire width direction. The sidewall portions 4 formed in this mannerare curved in a direction that protrudes outward in the tire widthdirection when viewed in a tire meridian cross-section, and are portionsthat are exposed to the outermost side in the tire width direction ofthe pneumatic tire 1.

Additionally, the bead portions 5 are disposed on the inner side in thetire radial direction of each of the pair of sidewall portions 4, and apair of the bead portions 5 are disposed on both sides of the tireequatorial plane CL in the tire width direction. Each of the beadportions 5 includes a bead core 11 and a bead filler 12. The bead core11 is formed by winding a bead wire, which is a steel wire, into a ringshape. The bead filler 12 is a rubber material that is disposed in thespace formed by an end portion of the carcass layer 6 in the tire widthdirection being folded back at the position of the bead core 11.

These sidewall portions 4 and bead portions 5 are included in the tireside portion 20 located on both sides in the tire width direction. Inthe present embodiment, the tire side portion 20 refers to a regionbetween a position on the inner side in the tire radial direction of thetread rubber 18 and a bead heel 14 that is an end portion on the innercircumferential surface of the bead portion 5 on the tire widthdirection outer side.

The end portions of the carcass layer 6 in the tire width direction arefolded back around the pair of bead cores 11 from the inner side in thetire width direction to the outer side in the tire width direction, andthe carcass layer 6 is stretched in a toroidal shape in the tirecircumferential direction to form the framework of the tire. The carcasslayer 6 is made of a plurality of coating rubber-covered carcass cords(not illustrated) disposed side by side with an angle with respect tothe tire circumferential direction along the tire meridian direction atan angle with respect to the tire circumferential direction. The carcasscords are made of organic fibers such as polyester, rayon, nylon, andthe like. The carcass layer 6 is provided with at least one layer.

The belt layer 7 has a multilayer structure in which at least two belts7 a, 7 b are layered, in the tread portion 2, the outer circumference ofthe carcass layer 6 is arranged on the outer side in the tire radialdirection, and the carcass layer 6 is covered in the tirecircumferential direction. The belts 7 a and 7 b are formed by coating aplurality of cords (not illustrated) that are disposed side by side at apredetermined angle (for example, 20° to 30°) with respect to the tirecircumferential direction with a rubber coating. The cord is made, forexample, of steel or an organic fiber such as polyester, rayon, nylon orthe like. The overlapping belts 7 a and 7 b are arranged so that thecords intersect with each other.

The belt reinforcing layer 8 is disposed on the outer side of the beltlayer 7 in the tire radial direction, i.e. on the outer circumferencethereof, and covers the belt layer 7 in the tire circumferentialdirection. The belt reinforcing layer 8 is formed by a plurality ofrubber-coated cords (not illustrated) disposed substantially parallel tothe tire circumferential direction and disposed side by side in the tirewidth direction. The cord is made of steel or an organic fiber such aspolyester, rayon, nylon, or the like, and the cord angle is within arange of ±5° with respect to the tire circumferential direction. In thepresent embodiment, the belt reinforcing layer 8 is layered in twolayers: a belt cover 8 a disposed so as to cover the entire belt layer 7in the tire width direction, and an edge cover 8 b provided only on theouter side in the tire radial direction of the belt cover 8 a near theend portion of the belt layer 7 in the tire width direction. The beltreinforcing layer 8 may have a configuration other than this, and may becomposed of only the belt cover 8 a disposed to cover the entire beltlayer 7 or the edge cover 8 b disposed to cover the end portion of thebelt layer 7 in the tire width direction. The belt reinforcing layer 8may be disposed so as to overlap at least the end portion in the tirewidth direction of the belt layer 7. The belt reinforcing layer 8configured as described above is disposed by winding a band-like stripmaterial having a width of about 10 mm in the tire circumferentialdirection.

The inner liner 9 is arranged along the carcass layer 6 on the innerside of the carcass layer 6 or on the inner side of the carcass layer 6in the pneumatic tire 1.

FIG. 2 is a detailed view of a tire side portion 20 outside the vehiclemounting direction in the pneumatic tire 1 illustrated in FIG. 1. In thepneumatic tire 1 according to this embodiment, a plurality of protrusionportions 30 are formed on the tire side surface 21 that is the surfaceof the tire side portion 20. The plurality of protrusion portions 30 areformed so as to respectively project from the tire side surface 21 andextend along the tire side surface 21. Of the tire side portions 20located on both sides in the tire width direction, the protrusionportions 30 are formed on the tire side portion 20 on the outer side inthe vehicle mounting direction. The protrusion portions 30 areprotrusion portions that protrude from a reference surface excluding apattern, characters, irregularities, and the like on the tire sidesurface 21.

Each of the plurality of protrusion portions 30 is disposed on the outerside in the tire radial direction in an arrangement possible region PAthat is a region from a position of 15% to a position of 85% of the tirecross-sectional height SH from the rim diameter reference position BL,which is a reference position on the inner side in the tire radialdirection of the tire cross-sectional height SH. The tire cross-sectionheight SH here is the distance in the tire radial direction between therim diameter reference position BL and the portion of the tread portion2 that is located on the outermost side in the tire radial direction.The rim diameter reference position BL is a line in the tire axialdirection that passes through the rim diameter defined by the JATMAstandard. In other words, the tire cross-sectional height SH is obtainedby mounting the pneumatic tire 1 on a regular rim and filling theregular internal pressure, and is ½ of the difference between the tireouter diameter and the rim diameter when no load is applied to thepneumatic tire 1.

In addition, here, a regular rim refers to a “standard rim” defined byJATMA (The Japan Automobile Tyre Manufacturers Association, Inc.), a“Design Rim” defined by TRA (The Tire & Rim Association, Inc.), or a“Measuring Rim” defined by ETRTO (The European Tyre and Rim TechnicalOrganisation). Moreover, a regular internal pressure refers to a“maximum air pressure” defined by JATMA, the maximum value in “TIRE LOADLIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or“INFLATION PRESSURES” defined by ETRTO.

In addition, each of the plurality of protrusion portions 30 is formedso as to straddle the tire maximum width position W on the tire sidesurface 21 in the tire radial direction. The tire maximum width positionW is the position in the tire radial direction at which the dimension inthe tire width direction is a maximum, excluding structures such aspatterns and characters protruding from the tire side surface 21 whenthe pneumatic tire 1 is mounted on a regular rim, is filled with regularinternal pressure, and no load is applied to the pneumatic tire 1. Notethat in a tire provided with a rim protect bar (which is provided alongthe tire circumferential direction and projects outward in the tirewidth direction) for protecting the rim, the position of the rim protectbar is the position where the dimension in the tire width direction is amaximum; however, the tire maximum width position W defined in thepresent embodiment excludes the rim protect bar.

Furthermore, the tire side portions 20 disposed on both sides in thetire width direction have a thickness Ga at the tire maximum widthposition W within a range of no less than 2 mm and no more than 9 mm. Inthis case, the thickness Ga of the tire side portion 20 does not includethe height of the protrusion portions 30. In other words, in the tireside portion 20, the distance from the tire side surface 21 at the tiremaximum width position W to the tire inner surface is within a range ofno less than 2 mm and no more than 9 mm. The thickness Ga of the tireside portion 20 at the tire maximum width position W is preferably in arange of no less than 2 mm and no more than 6 mm, and more preferably iswithin a range of no less than 2.5 mm and no more than 5 mm.

FIG. 3 is a view in the direction of arrow A-A in FIG. 2. The protrusionportions 30 are formed on one tire side portion 20 within a range of noless than 2 and no more than 16, and in the present embodiment, theprotrusion portions 30 are formed at eight sections of one tire sideportion 20. The eight protrusion portions 30 are discontinuouslyarranged at equal intervals in the tire circumferential direction.Moreover, the eight protrusion portions 30 are formed in substantiallythe same shape, and extend in the tire circumferential direction alongthe tire side surface 21 and are inclined in the tire radial directionwith respect to the tire circumferential direction. Note that preferablythe protrusion portions 30 formed on one tire side portion 20 are withina range of no less than 4 and no more than 12.

FIG. 4 is a detailed view of portion B of FIG. 3. The protrusionportions 30 extending in the tire circumferential direction are suchthat, a relative angle α in the tire circumferential direction betweenthe two protrusion portion end position lines Lc that respectivelyextend in the tire radial direction through different end portions 31 ofboth end portions 31 in the extending direction of the protrusionportions 30, or in other words, an angle α formed by two protrusionportion end position lines Lc is within a range of no less than 6% andno more than 50% of the angle 2π of one round in the tirecircumferential direction. In other words, each of the plurality ofprotrusion portions 30 disposed on one tire side portion 20 extends inthe tire circumferential direction within a range where the angle α isno less than 6% and no more than 50% of the angle 2π of one round in thetire circumferential direction. The angle α defined in this way is anangle in the tire circumferential direction in the range in which oneprotrusion portion 30 is disposed, or in other words, is an extensionangle of the protrusion portion 30 in the tire circumferentialdirection.

Note that in the protrusion portion 30, the angle α is preferably withina range of no less than 8% and no more than 40%, and more preferably iswithin a range of no less than 10% and no more than 30% the angle 2π ofone round in the tire circumferential direction.

In addition, each protrusion portion 30 includes at least one bendportion 40 at a position where the extending direction of the protrusionportion 30 changes, and each protrusion portion 30 includes a pluralityof bend portions 40. The number of bend portions 40 of one protrusionportion 30 is preferably within a range of no less than two and no morethan four. Moreover, each protrusion portion 30 includes a plurality ofextending portions 50 defined by the bend portions 40. In this case, theextending portions 50 are formed in a single arc shape or a singlelinear shape and each extends along the tire side surface 21. Inaddition, the single arc shape referred to here is a shape in which,when the extending portion 50 is formed curved, a difference in arelative ratio between the respective radii of curvature at the positionwith the largest radius of curvature and the position with the smallestradius of curvature is 10% or less. Furthermore, the single straightline shape is a shape in which the change in the extending direction ofthe extending portion 50 is 5° or less. Additionally, in a case wheretwo extending portions 50 defined by a bend portion 40 are both in asingle arc shape, the position of the inflection point is the bendportion 40, and in a case where the extending portions 50 are connectedby an arc having a minimum radius of curvature, the bend portion 40 is arange in which an arc having a minimum radius of curvature is formed.

In the present embodiment, each protrusion portion 30 includes two bendportions 40 and three extending portions 50 defined by the two bendportions 40. In other words, each protrusion portion 30 includes threeextending portions 50: a first extending portion 51, a second extendingportion 52, and a third extending portion 53. Of these, the firstextending portion 51 is the extending portion 50 having the longestlength among the plurality of extending portions 50 of the singleprotrusion portion 30. The second extending portion 52 is an extendingportion 50 continuous from the first extending portion 51 via the bendportion 40. Moreover, the third extending portion 53 is located on theopposite side to the side where the first extending portion 51 islocated in the extending direction of the second extending portion 52,and is an extending portion 50 that is continuous from the secondextending portion 52 via the bend portion 40. In other words, of theplurality of extending portions 50, only one end portion of the firstextending portion 51 and the third extending portion 53 is defined by abend portion 40 in the extending direction of the first extendingportion 51 and the third extending portion 53, and both end portions ofthe second extending portion 52 in the extending direction of the secondextending portion 52 are defined by a bend portion 40.

Moreover, the first extending portion 51 is disposed on the outermostside in the tire radial direction among the plurality of extendingportions 50, and the protrusion portion 30 is inclined with respect tothe tire circumferential direction in a direction from the outer side inthe tire radial direction toward the inner side in the tire radialdirection while going from the first extending portion 51 side towardthe third extending portion 53 side. Therefore, the second extendingportion 52 is disposed further on the inner side in the tire radialdirection than the first extending portion 51, and the third extendingportion 53 is disposed further on the inner side in the tire radialdirection than the second extending portion 52.

The plurality of protrusion portions 30 formed on one tire side portion20 are such that the inclination directions in the tire radial directionwhen going in a predetermined direction in the tire circumferentialdirection are all in the same direction (see FIG. 3). Therefore, theplurality of first extending portions 51 included in the plurality ofprotrusion portions 30 also have the same direction of inclination inthe tire radial direction with respect to the tire circumferentialdirection. More specifically, the first extending portion 51 inclineswith respect to the tire circumferential direction in a direction fromthe inner side to the outer side in the tire radial direction whilegoing from the leading side to the trailing side in the rotationdirection of the pneumatic tire 1. Moreover, similarly, the secondextending portion 52 and the third extending portion 53 are alsoinclined with respect to the tire circumferential direction in adirection from the inner side to the outer side in the tire radialdirection while going from the leading side to the trailing side in therotation direction of the pneumatic tire 1.

In addition, of the plurality of extending portions 50 included in theprotrusion portion 30, the second extending portion 52 is such that theinclination in the tire radial direction with respect to the tirecircumferential direction is larger than the inclination of the firstextending portion 51 in the tire radial direction with respect to thetire circumferential direction. Furthermore, the second extendingportion 52 has a greater inclination in the tire radial direction withrespect to the tire circumferential direction than the third extendingportion 53. In other words, the first extending portion 51, the secondextending portion 52, and the third extending portion 53 all have thesame inclination direction in the tire radial direction when going in apredetermined direction in the tire circumferential direction, while theinclination in the tire radial direction with respect to the tirecircumferential direction is greatest in the second extending portion52.

In addition, the first extending portion 51 having the longest lengthamong the plurality of extending portions 50 is such that the length C1(see FIG. 7) thereof is within a range of no less than 1.0 and no morethan 6.0 times the height FH (see FIG. 6) of the arrangement possibleregion PA in the tire radial direction. In other words, the firstextending portion 51 has a length C1 within a range of no more than 1.0times and no less than 6.0 times 70% of the tire cross-sectional heightSH. Note that the length C1 of the first extending portion 51 ispreferably within a range of no less than 1.5 and no more than 5.0 timesthe height FH of the arrangement possible region PA in the tire radialdirection.

Moreover, the first extending portion 51 is such that, of both endportions 51 a in the extending direction of the first extending portion51, a relative angle β in the tire circumferential direction between thetwo first extending portion end position lines Le extending in the tireradial direction through the different end portions 51 a, or in otherwords, the angle β formed by the two first extending portion endposition lines Le is formed to be within the range 0.60≤(β/α)≤0.90 withrespect to the angle α. This angle β is an angle in the tirecircumferential direction in the range in which one first extendingportion 51 is disposed, or in other words, is an extension angle of thefirst extending portion 51 in the tire circumferential direction.

Note that the angle β of the first extending portion 51 with respect tothe angle α of the protrusion portion 30 is preferably within the range0.70≤(β/α)≤0.85.

The first extending portion 51 formed in this manner has a length C1(see FIG. 7) within a range of no less than 1.5 and no more than 30times the length C2 of the second extending portion 52 (see FIG. 7).Furthermore, the length C1 of the first extending portion 51 is within arange of no less than 1.2 and no more than 25 times the length C3 (seeFIG. 7) of the third extending portion 53, which is the extendingportion 50 other than the second extending portion 52 and the firstextending portion 51. Note that the length C1 of the first extendingportion 51 is preferably within a range of no less than 3 and no morethan 20 times the length C2 of the second extending portion 52, and morepreferably is within a range of no less than 5 no more than 15 times thelength of C2. The length C1 of the first extending portion 51 ispreferably within a range of no less than 2 and no more than 20 timesthe length C3 of the third extending portion 53, and more preferably iswithin a range of no less than 3 and no more than 15 times the lengthC3.

FIG. 5 is a detailed view of portion B of FIG. 3, and is an explanatorydiagram of the position at which the protrusion portion 30 is disposed.The protrusion portion 30 formed to be inclined in the tire radialdirection with respect to the tire circumferential direction is suchthat the relationship between the distance Dmax in the tire radialdirection between the tire outer diameter portion 25 and the innermostportion of the protrusion portion 30 in the tire radial direction andthe distance Dmin in the tire radial direction between the outermostportion of the protrusion portion 30 in the tire radial direction andthe tire outer diameter portion 25 is within the range1.2≤(Dmax/Dmin)≤3.5. The tire outer diameter portion 25 in this case isa portion that becomes the outer diameter of the pneumatic tire 1, or inother words, is a portion that is located on the outermost side in thetire radial direction in the tread portion 2.

Moreover, the distance Dmax is within a range of no less than 0.30 andno more than 0.70 times the tire cross-sectional height SH.

Note that preferably the protrusion portion 30 is such that therelationship between the distance Dmax and the distance Dmin is withinthe range 1.5≤(Dmax/Dmin)≤2.5. Furthermore, the distance Dmax ispreferably within a range of no less than 0.35 and no more than 0.65times the tire cross-sectional height SH, and more preferably is withina range of no less than 0.40 and no more than 0.60 times the tirecross-sectional height SH.

More specifically, the protrusion portion 30 is inclined with respect tothe tire circumferential direction in a direction from the outer side inthe tire radial direction to the inner side in the tire radial directionwhile going from the first extending portion 51 side to the thirdextending portion 53 side, so of the protrusion portion 30, the portionlocated on the innermost side in the tire radial direction is the endportion 31 on the third extending portion 53 side of both end portions31 in the extending direction of the protrusion portion 30. Therefore,the distance Dmax is a distance in the tire radial direction between theend portion 31 on the third extending portion 53 side of the protrusionportion 30 and the tire outer diameter portion 25. Additionally, aportion of the protrusion portion 30 located on the outermost side inthe tire radial direction is the end portion 31 on the first extendingportion 51 side of both end portions 31 in the extending direction ofthe protrusion portion 30. Therefore, the distance Dmin is a distance inthe tire radial direction between the end portion 31 on the firstextending portion 51 side of the protrusion portion 30 and the tireouter diameter portion 25.

FIG. 6 is a detailed view of portion B of FIG. 3, and is an explanatorydiagram of the position where the protrusion portion 30 is disposed withrespect to the arrangement possible region PA. Furthermore, the firstextending portion 51 is such that the relationship between the distanceAmax in the tire radial direction between the innermost portion of thefirst extending portion 51 in the tire radial direction and the outerdiameter portion PAo of the arrangement possible region PA and thedistance Amin in the tire radial direction between the outermost portionof the first extending portion 51 in the tire radial direction and theouter diameter portion PAo of the arrangement possible region PA iswithin the range 1.0≤(Amax/Amin)≤3.5. The outer diameter portion PAo ofthe arrangement possible region PA in this case is a position thatdefines the outer end of the arrangement possible region PA in the tireradial direction, or in other words, is a position at 85% of the tirecross-sectional height SH from the rim diameter reference position BL tothe outer side in the tire radial direction (see FIG. 2). Furthermore,the distance Amin is such that the relationship with the height FH ofthe arrangement possible region PA in the tire radial direction iswithin a range 0≤Amin≤(FH×0.3).

More specifically, the first extending portion 51 is inclined withrespect to the tire circumferential direction in a direction from theouter side in the tire radial direction to the inner side in the tireradial direction while going from the side of the end portion 51 aopposite to the side where the second extending portion 52 is located,toward the side where the second extending portion 52 is located, so ofthe first extending portion 51, the portion located on the innermostside in the tire radial direction is the end portion 51 a on the secondextending portion 52 side of both end portions 51 a in the extendingdirection of the first extending portion 51. Therefore, the distanceAmax is the distance in the tire radial direction between the endportion 51 a of the first extending portion 51 on the second extendingportion 52 side and the outer diameter portion PAo of the arrangementpossible region PA, and in the first extending portion 51, is thedistance at a position where the distance in the tire radial directionfrom the outer diameter portion PAo of the arrangement possible regionPA is the largest. In other words, the first extending portion 51 issuch that the portion where the bend portion 40 that defines the firstextending portion 51 and the second extending portion 52 is located, islocated at a position in the first extending portion 51 where thedistance in the tire radial direction from the outer diameter portionPAo of the arrangement possible region PA is the largest.

Moreover, a portion of the first extending portion 51 located on theoutermost side in the tire radial direction is the end portion 51 a ofboth end portions 51 a in the extending direction of the first extendingportion 51 on the opposite side of the side where the second extendingportion 52 is located. Therefore, the distance Amin is the distance inthe tire radial direction between the end portion 51 a of the protrusionportion 30 on the side opposite to the side where the second extendingportion 52 is located and the outer diameter portion PAo of thearrangement possible region PA, and in the first extending portion 51,is the distance at a position where the distance in the tire radialdirection from the outer diameter portion PAo of the arrangementpossible region PA is the smallest.

Note that the first extending portion 51 is such that the relationshipbetween the distance Amax and the distance Amin is preferably within therange 1.0≤(Amax/Amin)≤2.0. Moreover, the distance Amin is such thatpreferably the relationship between the arrangement possible region PAand the height FH in the tire radial direction is within the range0≤Amin≤(FH×0.2).

FIG. 7 is a detailed view of the protrusion portion 30 illustrated inFIG. 5. The protrusion portion 30 is such that the length C0 along theshape of the protrusion portion 30, or in other words, the length C0 ofthe protrusion portion 30 along the extending direction is within arange of no less than 1.5 and no more than 7.0 times the height FH (seeFIG. 6) of the arrangement possible region PA in the tire radialdirection. Note that the length C0 of the protrusion portion 30 ispreferably within a range of no less than 2.0 and no more than 6.0 timesthe height FH of the arrangement possible region PA in the tire radialdirection, and even more preferably is within a range of no less than2.5 and no more than 5.5 times the height FH.

Furthermore, the protrusion portion 30 is such that the first extendingportion 51 is the longest extending portion 50 among the plurality ofextending portions 50 included in the protrusion portion 30, so thefirst extending portion 51 has a length C1 along the shape of the firstextending portion 51 that is longer than the second extending portion 52and the third extending portion 53. In other words, the length C1 of thefirst extending portion 51 is longer than the length C2 of the secondextending portion 52 along the shape of the second extending portion 52,or the length C3 of the third extending portion 53 along the shape ofthe third extending portion 53.

Moreover, the protrusion portion 30 is such that an angle θ1 formed by acenter line 51 c in the width direction of the first extending portion51 and a center line 52 c in the width direction of the second extendingportion 52 is within the range 90°≤θ1≤170°. In addition, the protrusionportion 30 is such that the angle θ2 formed by the center line 52 c inthe width direction of the second extending portion 52 and the centerline 53 c in the width direction of the third extending portion 53 isalso within the range 90°≤02≤170°. In other words, the protrusionportion 30 including a plurality of extending portions 50 defined bybend portions 40 is such that the angle θn formed by the center lines ofthe two extending portions 50 that are continuous through the bendportion 40 in the respective width directions is within the range90°≤θn≤170°. Note that these angles θ1 and 02, or in other words, theangle θn, are preferably in a range of no less than 110° and no morethan 160°.

FIG. 8 is an explanatory diagram of the angle θ1 formed by the centerline Mc of the first extending portion 51 and the center line 52 c of asecond extending portion 52 illustrated in FIG. 7. Here, the extendingportion 50 is formed in a single arc shape or a single straight lineshape, so the first extending portion 51, the second extending portion52, and the third extending portion 53 may also be formed in a singlearc shape. In a case where the extending portion 50 is formed in an arcshape, the angle θn that is formed by the center lines of the twoextending portions 50 that are continuous via the bend portion 40 is anangle between imaginary lines connecting the bend portion 40 and aposition where a circle having a predetermined radius whose center islocated in the bend portion 40 and the center line of each extendingportion 50 intersect, and for convenience, the angle θn is the anglethat is formed by the center lines of the two extending portions 50.

For example, the angle θ1 formed by the center line 51 c of the firstextending portion 51 and the center line 52 c of the second extendingportion 52 in a case where at least one of the first extending portion51 and the second extending portion 52 is formed in a single arc shapeis defined by a position where a circle having a predetermined radiuscentered on the bend portion 40 and the center line 51 c of the firstextending portion 51 and the center line 52 c of the second extendingportion 52 intersect with each other, and for convenience sake, theangle between the imaginary lines connecting each of the portions 40will be referred to as the angle θ1.

More specifically, of the first extending portion 51 and the secondextending portion 52, an imaginary circle Vc having a radius that ishalf the length of the second extending portion 52 that is the extendingportion 50 on the shorter side is set so that the center is located atthe bend portion 40, and a line connecting the bend portion 40 and theintersection 51 x of the center line 51 c of the first extending portion51 and the imaginary circle Vc is defined as a temporary center line 51c 1 of the first extending portion 51. Similarly, a line connecting anintersection portion 52 x of the center line 52 c of the secondextending portion 52 and the imaginary circle Vc and the bend portion 40is defined as a temporary center line 52 c 1 of the second extendingportion 52. The angle formed by the temporary center line 51 c 1 of thefirst extending portion 51 and the temporary center line 52 c 1 of thesecond extending portion 52 set as described above may be taken to be anangle θ1 that is formed by the center line Mc in the width direction ofthe first extending portion 51 and the center line 52 c of the secondextending portion 52 in the width direction.

The first extending portion 51 and the second extending portion 52 aresuch that the angle θ1 set in this manner is within the range90°≤θ1≤170°.

The angle θ2 formed by the center line 52 c of the second extendingportion 52 in the width direction and the center line 53 c of the thirdextending portion 53 in the width direction may be derived by the samemethod.

The second extending portion 52 is such that the inclination in the tireradial direction with respect to the tire circumferential direction islarger than the inclination of the first extending portion 51 and thethird extending portion 53 in the tire radial direction with respect tothe tire circumferential direction; however, the inclination of thefirst extending portion 51, the second extending portion 52, and thethird extending portion 53 in the tire radial direction with respect tothe tire circumferential direction may also be derived based on a circlehaving a radius of a predetermined size with the bend portion 40 as thecenter.

FIG. 9 is an explanatory diagram of a comparison of the inclination ofan extending portion 50 illustrated in FIG. 7. For example, whencomparing the inclinations of the first extending portion 51 and thesecond extending portion 52 in the tire radial direction with respect tothe tire circumferential direction, as in the method of obtaining theangle θ1 formed by the center line 51 c of the first extending portion51 and the center line 52 c of the second extending portion 52, thetemporary center line 51 c 1 of the first extending portion 51 and thetemporary center line 52 c 1 of the second extending portion 52 are setusing the imaginary circle Vc. In addition, a reference circle Lb1 whosecenter is located on the tire rotation axis and that passes through thecenter of the imaginary circle Vc, or in other words, the connectingportion between the temporary center line 51 c 1 of the first extendingportion 51 and the temporary center line 52 c 1 of the second extendingportion 52 is set, and a tangent line Lt1 of the reference circle Lb1passing through the center of the imaginary circle Vc is set. The secondextending portion 52 is such that the angle θa2 between the temporarycenter line 52 c 1 and the tangent line Lt1 set as described above issmaller than the angle θa1 between the temporary center line 51 c 1 andthe tangent line Lt1 of the first extending portion 51. Therefore, thesecond extending portion 52 is such that the inclination in the tireradial direction with respect to the tire circumferential direction islarger than the inclination of the first extending portion 51 in thetire radial direction with respect to the tire circumferentialdirection.

When comparing the inclinations of the second extending portion 52 andthe third extending portion 53 in the tire radial direction with respectto the tire circumferential direction, of the second extending portion52 and the third extending portion 53, the imaginary circle Vc having aradius that is half the length of the second extending portion 52 thatis the extending portion 50 on the shorter side is set so that thecenter is positioned in the bend portion 40 that defines the secondextending portion 52 and the third extending portion 53, and a lineconnecting the intersection portion 52 x of the center line 52 c of thesecond extending portion 52 and the imaginary circle Vc and the bendportion 40 is defined as a temporary center line 52 c 1′ of the secondextending portion 52. Similarly, a line connecting the intersection 53 xof the center line 53 c of the third extending portion 53 and theimaginary circle Vc and the bend portion 40 is defined as a temporarycenter line 53 c 1 of the third extending portion 53.

In addition, a reference circle Lb3 whose center is located on the tirerotation axis and that passes through the center of the imaginary or inother words, the connecting portion between the temporary center line 52c 1′ of the second extending portion 52 and the temporary center line 53c 1 of the third extending portion 53 is set, and a tangent line Lt3 ofthe reference circle Lb3 passing through the center of the imaginarycircle Vc is set. The second extending portion 52 is such that the angleθa2′ between the temporary center line 52 c 1 and the tangent line Lt3set as described above is larger than the angle θa3 between thetemporary center line 53 c 1 and the tangent line Lt3 of the thirdextending portion 53. Therefore, the second extending portion 52 is suchthat the inclination in the tire radial direction with respect to thetire circumferential direction is larger than the inclination of thethird extending portion 53 in the tire radial direction with respect tothe tire circumferential direction. In other words, the second extendingportion 52 is such that the inclination in the tire radial directionwith respect to the tire circumferential direction is larger than theinclination of the first extending portion 51 and the third extendingportion 53 in the tire radial direction with respect to the tirecircumferential direction.

FIG. 10A is a cross-sectional view of D1-D1 of FIG. 7. FIG. 10B is across-sectional view of D2-D2 of FIG. 7. FIG. 10C is a cross-sectionalview of D3-D3 of FIG. 7. The protrusion portion 30 is formed such thatthe cross-sectional shape when viewed in the extending direction of theprotrusion portion 30 is a substantially rectangular shape in which theheight direction of the protrusion portion 30 is the longitudinaldirection. Moreover, each of the plurality of extending portions 50included in the protrusion portion 30 has the width Wc and the height Hcthat change at a position where crossing the bend portion 40. The widthWc of the extending portion 50 in this case is the width of theextending portion 50 in the direction orthogonal to the extendingdirection of the extending portion 50 in a case of viewing the extendingportion 50 in the direction in which the protrusion portion 30 projectsfrom the tire side surface 21. Furthermore, the height Hc of theextending portion 50 is the height from the tire side surface 21.

The plurality of extending portions 50 have different widths Wc andheights Hc defined in this way for each extending portion 50. In otherwords, in the protrusion portion 30, the first extending portion 51, thesecond extending portion 52, and the third extending portion 53 havedifferent widths Wc and heights Hc. In the present embodiment, the widthW2 of the second extending portion 52 is such that the average width islarger than the average width of each of the width W1 of the firstextending portion 51 and the width W3 of the third extending portion 53.In addition, the height H2 of the second extending portion 52 is alsosuch that the average height is higher than the average height of eachof the height H1 of the first extending portion 51 and the height H3 ofthe third extending portion 53.

FIG. 11 is an explanatory diagram of the position of the maximum widthportion Wm of the protrusion portion 30. The plurality of extendingportions 50 are such that in one extending portion 50, the width Wc iswithin a range of no less than 0.1 and no more than 1.0 times themaximum width of the extending portion 50. Moreover, of the plurality ofextending portions 50, the first extending portion 51 that is theextending portion 50 having the longest length is such that the maximumwidth is within a range of no less than 0.5 mm and no more than 7.0 mm.Furthermore, the second extending portion 52 is such that the maximumwidth is larger than the maximum width of the first extending portion51, or more specifically, the second extending portion is such that themaximum width is within a range of no less than 1.5 and no more than 5times the maximum width of the first extending portion 51.

Additionally, the second extending portion 52 is such that even withrespect to the third extending portion 53, the maximum width is largerthan the maximum width of the third extending portion 53. Therefore, theprotrusion portion 30 is such that the maximum width portion Wm, whichis the portion having the maximum width in the protrusion portion 30, islocated in the second extending portion 52. The protrusion portion 30 issuch that the position in the tire radial direction of the maximum widthportion Wm of the protrusion portion 30 located in the second extendingportion 52 in this way is included within a range of no less than 0.40and no more than 0.60 times the tire cross-sectional height SH from therim diameter reference position BL to the outer side in the tire radialdirection. Note that the position of the maximum width portion Wm of theprotrusion portion 30 in the tire radial direction is preferablyincluded within a range of no less than 0.45 and no more than 0.55 timesthe tire cross-sectional height SH from the rim diameter referenceposition BL to the outer side in the tire radial direction.

FIG. 12 is a schematic diagram of the protrusion portion 30 illustratedin FIG. 7 as viewed in the E-E direction. The protrusion portion 30 issuch that The height Hc is different for each extending portion 50, soin other words, the height Hc from the tire side surface 21 differsdepending on the position of the protrusion portion 30, and the heightHc from the tire side surface 21 and the way the height Hc changes aredifferent for each extending portion 50. For example, the firstextending portion 51 is such that the height H1 from the tire sidesurface 21 decreases going from the side on which the second extendingportion 52 is located toward the end portion 51 a located on theopposite side to the side on which the second extending portion 52 islocated. The first extending portion 51 formed in this manner isarranged further on the outer side in the tire radial direction than thesecond extending portion 52 and is inclined in the tire radial directionwith respect to the tire circumferential direction, so the firstextending portion 51 is such that the height H1 from the tire sidesurface 21 decreases going toward the outer side in the tire radialdirection, and the height H1 from the tire side surface 21 becomeslowest at the position of the end portion 51 a on the outer side in thetire radial direction (see FIG. 2). In other words, the first extendingportion 51 is such that the height H1 from the tire side surface 21 isthe lowest at the position where the distance in the tire radialdirection between the arrangement possible region PA and the outerdiameter portion PAo is the smallest distance Amin (see FIG. 6).

Moreover, similar to the first extending portion 51, the third extendingportion 53 also is such that the height H3 from the tire side surface 21decreases from the side where the second extending portion 52 is locatedto the end portion 53 a which is located on the opposite side to theside where the second extending portion 52 is located (see FIG. 12). Thethird extending portion 53 formed in this manner is disposed on theinner side in the tire radial direction with respect to the secondextending portion 52 and is inclined in the tire radial direction withrespect to the tire circumferential direction, so the third extendingportion 53 is such that the height H3 from the tire side surface 21decreases going toward the inner side in the tire radial direction, andthe height H3 from the tire side surface 21 becomes lowest at theposition of the end portion 53 a on the inner side in the tire radialdirection (see FIG. 2).

In addition, of the plurality of extending portions 50, the highestextending portion 56, which is the extending portion 50 having thehighest average extending portion height that is the average height fromthe tire side surface 21 for each extending portion 50, is one of theextending portions 50 other than the first extending portion 51.

In the present embodiment, the highest extending portion 56 becomes thesecond extending portion 52, which is the extending portion 50 of theplurality of extending portions 50 that is continuous from the firstextending portion 51 via the bend portion 40. Therefore, the highestextending portion 56 is the extending portion 50 of the plurality ofextending portions 50 having the largest inclination in the tire radialdirection with respect to the tire circumferential direction. The secondextending portion 52, which is the highest extending portion 56, has anaverage extending portion height within a range of no less than 3 mm andno more than 10 mm.

In addition, of the plurality of extending portions 50, the extendingportion 50 other than the highest extending portion 56 has an averageextending portion height that is within a range of no less than 0.1 andno more than 0.8 times an average extending portion height of thehighest extending portion 56.

In other words, the first extending portion 51 and the third extendingportion 53, which are the extending portions 50 other than the highestextending portion 56, have an average extending portion height that iswithin a range of no less than 0.1 and no more than 0.8 times an averageextending portion height of the second extending portion 52, which isthe highest extending portion 56.

Moreover, the position in the tire radial direction of the maximumheight portion Hm, which is the portion where the height H2 of thesecond extending portion 52 that is the highest extending portion 56from the tire side surface 21 is the highest, is included within therange from the rim diameter reference position BL to the outer side inthe tire radial direction from a position where the height is 0.40 timesto 0.60 times the tire cross-sectional height SH (see FIG. 2). In otherwords, the protrusion portion 30 is such that the position in the tireradial direction of the maximum height portion Hm, which is the portionwhere the height from the tire side surface 21 is the highest, isincluded within the range from the rim diameter reference position BL tothe outer side in the tire radial direction from a position where theheight is no less than 0.40 and no more than 0.60 times the tirecross-sectional height SH. Note that the position of the maximum heightportion Hm of the protrusion portion 30 in the tire radial direction ispreferably included within the range from the rim diameter referenceposition BL to the outer side in the tire radial direction from aposition where the height is no less than 0.45 and no more than 0.55times the tire cross-sectional height SH.

In addition, the maximum height of the second extending portion 52 fromthe tire side surface 21 is within a range of no less than 1.1 times andno more than 3.0 times the maximum width of the second extending portion52. In other words, the second extending portion 52 is such that theheight Hc at the maximum height portion Hm is in a range of no less than1.1 and no more than 3.0 times the width We at the maximum width portionWm (see FIG. 11) of the second extending portion 52. On the other hand,the first extending portion 51 is such that the maximum height from thetire side surface 21 is in a range of no less than 1.1 and no more than5.0 times the maximum width of the first extending portion 51.

FIG. 13 is an explanatory diagram of substantial parallelism between thefirst extending portion 51 and the third extending portion 53. The firstextending portion 51 and the third extending portion 53 of theprotrusion portion 30 are such that the center line 51 c of the firstextending portion 51 in the width direction and the center line 53 c ofthe third extending portion 53 in the width direction are substantiallyparallel to each other. Parallel in this case means that the inclinationangles of the center line 51 c of the first extending portion 51 and thecenter line 53 c of the third extending portion 53 in the tire radialdirection with respect to the tire circumferential direction aresubstantially the same. In other words, the center line 51 c of thefirst extending portion 51 and the center line 53 c of the thirdextending portion 53 are such that difference between the angle θb1formed by an imaginary line 51 b intersecting the first extendingportion 51 and passing through the tire center and a center line 51 c ofthe first extending portion 51 and angle θ3 formed by an imaginary line53 b intersecting the third extending portion 53 and passing through thetire center and a center line 53 c of the third extending portion 53 iswithin a predetermined range. In the present embodiment, a form in whichthe difference in angles to be compared is within ±10° is calledsubstantially parallel.

More specifically, of the first extending portion 51 and the thirdextending portion 53, an imaginary circle Vp having a radius that ishalf the length of the third extending portion 53 that is the extendingportion 50 on the shorter side is set with the end portion 51 a of thefirst extending portion 51 near the third extending portion 53 as thecenter, and a line connecting the intersection 51 y of the center line51 c of the first extending portion 51 and the imaginary circle Vp andthe end 51 a of the first extending portion 51 is defined as a temporarycenter line 51 c 2 of the first extending portion 51. Similarly, theimaginary circle Vp is set with the end portion 53 a of the thirdextending portion 53 near the first extending portion 51 as the center,and a line connecting the intersection 53 y of the center line 53 c ofthe third extending portion 53 and the imaginary circle Vp and the endportion 53 a of the third extending portion 53 is a temporary centerline 53 c 2 of the third extending portion 53.

Furthermore, an imaginary line 51 b connecting the end portion 51 a ofthe first extending portion 51 near the third extending portion 53 andthe tire center, and an imaginary line 53 b connecting the end portion53 a of the third extending portion 53 near the first extending portion51 and the tire center are set.

The first extending portion 51 and the third extending portion 53 aresuch that the difference between the angle θb1 formed by the temporarycenter line 51 c 2 of the first extending portion 51 and the imaginaryline 51 b and the angle θ3 formed by the imaginary center line 53 c 2 ofthe third extending portion 53 and the imaginary line 53 b set asdescribed above is ±10°. Accordingly, the center line 51 c of the firstextending portion 51 and the center line 53 c of the third extendingportion 53 are such that the angles of inclination in the tire radialdirection with respect to the tire circumferential direction are almostthe same, and the center line 51 c of the first extending portion 51 andthe center line 53 c of the third extending portion 53 are substantiallyparallel to each other.

FIG. 14 is an explanatory diagram of an overlapping portion 55 betweenadjacent protrusion portions 30. The protrusion portion 30 includes theoverlapping portion 55 that is a portion that overlaps a differentprotrusion portion 30 in the tire circumferential direction. Morespecifically, the overlapping portion 55 is such that the positions ofthe protrusion portions 30 adjacent to each other in the tirecircumferential direction are the same in the tire circumferentialdirection while the positions in the tire radial direction aredifferent. In other words, the overlapping portion 55 is formed by twoprotrusion portions 30 adjacent in the tire circumferential direction,and is a portion of the protrusion portions 30 adjacent in the tirecircumferential direction overlapping in the tire circumferentialdirection.

That is, the protrusion portions 30 are formed to be inclined in thetire radial direction with respect to the tire circumferential directionwhile facing in the tire circumferential direction, so each protrusionportion 30 is such that one end portion 31 and an other end portion 31in the extending direction of the protrusion portion 30 have differentpositions in the tire radial direction. The plurality of protrusionportions 30 formed on one tire side portion 20 are such that theinclination directions in the tire radial direction with respect to thetire circumferential direction are all the same direction. Therefore,adjacent protrusion portions 30 are such that a position of the endportion 31 in the tire radial direction located closer to anotherprotrusion portion 30 is different from the one thereof. As a result,adjacent protrusion portions 30 are such that the protrusion portions 30can be overlapped with each other by locating the vicinities of the endportions 31 of different protrusion portions 30 to be close to eachother, within a range in which the different protrusion portions 30 aredisposed in the tire circumferential direction. The overlapping portion55 is formed by locating a part of each of the protrusion portions 30adjacent to each other in the tire circumferential direction within arange in the tire circumferential direction in which the other of theprotrusion portions 30 is disposed.

The overlapping portion 55 of the protrusion portion 30 formed in thisway is such that the angle γ in the tire circumferential direction ofthe range in which the overlapping portion 55 extends in the tirecircumferential direction is within the range 0.05≤(γ/α)≤0.30 withrespect to the angle α (see FIG. 4) in the tire circumferentialdirection in the range in which one protrusion portion 30 is disposed.The angle γ of the overlapping portion 55 is preferably within the range0.10≤(γ/α)≤0.20 with respect to the angle α of the protrusion portion30.

FIG. 15 is a detailed view of the overlapping portion 55 illustrated inFIG. 14. The two protrusion portions 30 that overlap at the overlappingportion 55 are such that the relationship between the maximum distancePmax and the minimum distance Pmin in a tire radial direction betweenthe overlapping portions is within the range 1.0≤(Pmax/Pmin)≤2.0. Inthis case, the maximum distance Pmax is the distance in the tire radialdirection at the portion where the distance between one protrusionportion 30 and another protrusion portion 30 in the tire radialdirection is the largest, in the overlapping portion 55 formed by theprotrusion portions 30 adjacent to each other in the tirecircumferential direction. The minimum distance Pmin is the distance inthe tire radial direction at the portion where the distance between oneprotrusion portion 30 and another protrusion portion 30 in the tireradial direction is the smallest, in the overlapping portion 55 formedby protrusion portions 30 adjacent to each other in the tirecircumferential direction. Among these, the minimum distance Pmin iswithin the range 0.15≤(Pmin/SH)≤0.30 with respect to the tirecross-sectional height SH.

Note that the maximum distance Pmax and the minimum distance Pmin in thetire radial direction between the overlapping portions of theoverlapping portion 55 are preferably in the range 1.0≤(Pmax/Pmin)≤1.5.That is, the maximum distance Pmax and the minimum distance Pmin may bePmax=Pmin, or in other words, the two protrusion portions 30 overlappingin the overlapping portion 55 may be parallel to each other. Moreover,the minimum distance Pmin with respect to the tire cross-sectionalheight SH is preferably within the range 0.18≤(Pmin/SH)≤0.25.

The plurality of protrusion portions 30 formed on one tire side portion20 all overlap protrusion portions 30 adjacent in the tirecircumferential direction (see FIG. 3). Therefore, the plurality ofprotrusion portions 30 formed on one tire side portion 20 are such thatby the protrusion portions 30 adjacent to each other overlapping eachother in the overlapping portion 55, one or more protrusion portions 30are provided at any position on the tire circumference.

Additionally, the protrusion portions 30 are such that the protrusionportions 30 adjacent to each other in the tire circumferential directionall overlap, so the sum of the angles α of the plurality of protrusionportions 30 formed on one tire side portion 20 is larger than the angle2π of one round in the tire circumferential direction. Morespecifically, the sum of the angles α of the plurality of protrusionportions 30 formed on one tire side portion 20 is within a range of noless than 105% and no more than 200% of the angle 2π of one round in thetire circumferential direction. Note that the sum of the angles α of theplurality of protrusion portions 30 formed on one tire side portion 20is preferably within a range of no less than 110% and no more than 190%,and more preferably is within a range of no less than 115% and no morethan 180% of the angle 2π of one round in the tire circumferentialdirection.

When mounting the pneumatic tire 1 according to this embodiment on avehicle, the rim wheel is fitted to the bead portion 5 to mount thepneumatic tire 1 on the rim wheel, and then the inner portion is filledwith air, and the rim wheel is mounted on the vehicle with the pneumatictire 1 in an inflated state. When doing this, the mounting directionwith respect to the vehicle and the rotation direction when mounted on avehicle are designated, so the pneumatic tire 1 according to the presentembodiment is mounted on the vehicle in the designated direction. Inother words, the pneumatic tire 1 is mounted on the vehicle in thedirection designated according to the mounting direction display portionand the rotation direction display portion attached to the sidewallportion 4. More specifically, the pneumatic tire 1 is mounted on thevehicle so that, of the tire side portions 20 located on both sides inthe tire width direction, the tire side portion 20 on the side where theprotrusion portions 30 are formed is positioned on the outer side in thevehicle mounting direction.

When a vehicle on which the pneumatic tire 1 is mounted travels, thepneumatic tire 1 rotates while the portion of the ground contact surface10 located below and facing the road surface comes in contact with theroad surface. The vehicle travels by transmitting a driving force or abraking force to the road surface or generating a turning force by africtional force between the ground contact surface 10 and the roadsurface. For example, in a case where a vehicle on which the pneumatictire 1 is mounted travels over a dry road surface, the vehicle travelsmainly by transmitting a driving force or a braking force to the roadsurface or generating a turning force by a frictional force between theground contact surface 10 and the road surface. In addition, whentraveling on a wet road surface, water between the ground contactsurface 10 and the road surface enters into the grooves such ascircumferential grooves 16, lug grooves and the like formed on theground contact surface 10, the vehicle travels while water is drainedbetween the ground contact surface 10 and the road surface by thesegrooves. Accordingly, the ground contact surface 10 is easily groundedon the road surface, and the frictional force between the ground contactsurface 10 and the road surface allows the vehicle to travel as desired.

Here, when the vehicle is traveling, the pneumatic tire 1 may come intocontact with a portion other than the ground contact surface 10. Forexample, when the pneumatic tire 1 rides up on a curb, or when thepneumatic tire 1 gets too close to the curb during parking, the tireside surface 21 may come in contact with the curb. In this case,cracking may occur in a portion of the tire side surface 21 that is incontact with the curb, and there is a possibility that the tire sideportion 20 may be damaged, and damage to the tire side portion 20 maycause a failure such as puncturing of the pneumatic tire 1.

On the other hand, in the pneumatic tire 1 according to this embodiment,protrusion portions 30 are formed on the tire side surface 21 of thetire side portion 20. Therefore, even when an obstacle such as a curbcomes into contact with the tire side surface 21, the obstacle comesinto contact with the protrusion portions 30, so it is possible tosuppress damage to the tire side portion 20 due to an obstacle cominginto contact with the tire side surface 21. Accordingly, scratchresistance may be improved.

Furthermore, the protrusion portions 30 formed on the tire side portion20 in this way are such that when the pneumatic tire 1 rotates duringtraveling of the vehicle, turbulent flow may be generated in the airaround the protrusion portions 30. In this way, an increase in airresistance may be suppressed. In other words, when the pneumatic tire 1rotates, a turbulent boundary layer is generated around the protrusionportions 30 projecting from the tire side surface 21, so it becomes moredifficult for air to separate from the tire side surface 21 due to thetire side surface 21 moving at high speed with respect to thesurrounding air. Therefore, it is possible to suppress an increase inthe air resistance caused by the air around the pneumatic tire 1separating from the tire side surface 21, and it is possible to reducethe rolling resistance when the pneumatic tire 1 rotates. In this way,fuel economy performance may be improved.

Further, the relative angle α in the tire circumferential directionbetween the two protrusion portion end position lines Lc respectivelypassing through both the end portions 31 of the protrusion portion 30 iswithin a range of no less than 6% and no more than 50% of the angle 2πof one round in the tire circumferential direction. Thus, the protrusionportion 30 can be easily brought into contact with an obstacle that islikely to come into contact with the tire side surface 21, and theprotrusion portion 30 can effectively generate turbulent flow whilesuppressing an increase in weight of the pneumatic tire 1. In otherwords, when the angle α is less than 6% of the angle 2π of one round inthe tire circumferential direction, the arrangement range of theprotrusion portion 30 in the tire circumferential direction is toosmall. Thus, whenever an obstacle such as a curb comes into contact withthe tire side surface 21, the obstacle is less likely to come intocontact with the protrusion portion 30. Thus, it is difficult for theprotrusion portion 30 to suppress damage to the tire side portion 20,and it is difficult for the protrusion portion 30 to protect the tireside portion 20. Further, when the angle α is less than 6% of the angle2π of one round in the tire circumferential direction, the arrangementrange of the protrusion portion 30 in the tire circumferential directionis too small. Thus, even when the tire side portion 20 is provided withthe protrusion portion 30, it may be difficult to generate turbulentflow in the air around the protrusion portion 30. In this case, when thepneumatic tire 1 rotates, it is difficult for the protrusion 30 tosuppress separation of the air around the tire pneumatic tire 1 from thetire side surface 20, and it is difficult to reduce the rollingresistance by suppressing an increase in air resistance during rotation.

Further, when the angle α exceeds 50% of the angle 2π of one round inthe tire circumferential direction, the arrangement range of theprotrusion portion 30 in the tire circumferential direction is toolarge. Thus, when the tire side portion 20 is provided with theprotrusion portion 30, the weight of the pneumatic tire 1 may beexcessively increased. In this case, even though an increase in airresistance is suppressed by the protrusion portion 30, the weight of thepneumatic tire 1 increases, which may degrade the rolling resistance.

In view of this, when the angle α is within a range of no less than 6%and no more than 50% of the angle 2π of one round in the tirecircumferential direction, the protrusion portion 30 can be easilybrought into contact with an obstacle that is likely to come intocontact with the tire side surface 21, and the protrusion portion 30 caneffectively generate turbulent flow while suppressing an increase inweight of the pneumatic tire 1. Accordingly, together with improvingscratch resistance by effectively suppressing damage to the tire sideportion 20 by the protrusion portions 30, an increase of air resistanceduring rotation of the pneumatic tire 1 can be reduced. Thus, rollingresistance can be reduced, and fuel economy performance can be improved.

Furthermore, the thickness Ga of the tire side portion 20 at the tiremaximum width position W is within a range of no less than 2 mm and nomore than 9 mm, so it is possible to reduce the weight of the pneumatictire 1 while suppressing damage to the tire side portion 20, and therolling resistance may be reduced. In other words, in a case where thethickness Ga of the tire side portion 20 at the tire maximum widthposition W is less than 2 mm, the thickness Ga of the tire side portion20 is too thin, so even though the protrusion portions 30 of the tireside portion 20 are provided, there is a risk that the tire side portion20 may be damaged when an obstacle comes in contact with the protrusionportions 30. Moreover, in a case where the thickness Ga of the tire sideportion 20 at the tire maximum width position W exceeds 9 mm, the weightof the tire side portion 20 becomes large, so there is a possibilitythat the rolling resistance may degrade.

On the other hand, the thickness Ga of the tire side portion 20 at thetire maximum width position W is within a range of no less than 2 mm andno more than 9 mm, so it is possible to reduce the weight of thepneumatic tire 1 while suppressing damage to the tire side portion 20,and the rolling resistance may be reduced. As a result, both scratchresistance and fuel economy performance may be achieved in a compatiblemanner.

Further, a relationship between the distance Dmax between the tire outerdiameter portion 25 and the innermost part in the tire radial directionand the distance Dmin between the tire outer diameter portion 25 and theoutermost part in the tire radial direction is within a range of1.2≤(Dmax/Dmin)≤3.5. Thus, the protrusion portion 30 can reduce therolling resistance more reliably, and the protrusion portion 30 can beeasily brought into contact with an obstacle that is likely to come intocontact with the tire side surface 21. In other words, when therelationship between the distance Dmax and the distance Dmin is(Dmax/Dmin)≤1.2, the shape in which the protrusion portion 30 isarranged is close to a shape along the tire circumferential direction.Thus, it is difficult for the protrusion portion 30 to generateturbulent flow. In this case, it is difficult to suppress the increasein air resistance when the pneumatic tire 1 rotates, which may make itdifficult to reduce the rolling resistance. Further, when therelationship between the distance Dmax and the distance Dmin is(Dmax/Dmin)>3.5, inclination of the protrusion portion 30 in the tireradial direction with respect to the tire circumferential direction maybe excessively large. Thus, in the tire circumferential direction, therange in which the protrusion portion 30 is not arranged may beexcessively large. In this case, it is difficult for the protrusionportion 30 to come into contact with an obstacle that is likely to comeinto contact with the tire side surface 21, which may make it difficultto suppress damage to the tire side portion 20.

In view of this, the relationship between the distance Dmax and thedistance Dmin is within a range of 1.2≤(Dmax/Dmin)≤3.5, the protrusionportion 30 can generate turbulent flow effectively, and the rollingresistance can be reduced more reliably. Furthermore, the protrusionportion 30 can be easily brought into contact with an obstacle that islikely to come into contact with the tire side surface 21. As a result,both scratch resistance and fuel economy performance may be achievedmore reliably in a compatible manner.

Further, in the protrusion portion 30, the distance Dmax between thetire outer diameter portion 25 and the innermost part in the tire radialdirection is within a range of no less than 0.30 and no more than 0.70times the tire cross-sectional height SH. Thus, the position at whichturbulent flow is generated by the protrusion portion 30 can be locatednear the center of the tire cross-sectional height SH in the tire radialdirection. Thus, the rolling resistance can be reduced more reliably. Inother words, when the distance Dmax is less than 0.30 times the tirecross-sectional height SH, the position at which the protrusion portion30 is arranged in the tire radial direction may be excessively inward inthe tire radial direction. Further, when the distance Dmax is largerthan 0.70 times the tire cross-sectional height SH, the position atwhich the protrusion portion 30 is arranged in the tire radial directionmay be excessively outward in the tire radial direction. In this case,the position at which turbulent flow is generated by the protrusionportion 30 may be excessively inward or outward in the tire radialdirection. Thus, it is difficult to effectively suppress the increase inair resistance when the pneumatic tire 1 rotates, which may make itdifficult to reduce the rolling resistance.

In view of this, when the distance Dmax is within a range of no lessthan 0.30 and no more than 0.70 times the tire cross-sectional heightSH, the position at which turbulent flow is generated by the protrusionportion 30 can be located near the center of the tire cross-sectionalheight SH in the tire radial direction. In this way, the rollingresistance may be more reliably reduced by the turbulent flow generatedby the protrusion portion 30. As a result, it is possible to morereliably improve fuel economy performance.

Moreover, the protrusion portion 30 is such that the tire maximum widthposition W on the tire side surface 21 is formed so as to extend acrossthe tire radial direction, so the position at which turbulent flow isgenerated by the protrusion portion 30 can be more reliably located nearthe center of the tire cross-sectional height SH in the tire radialdirection. In this way, the rolling resistance may be more reliablyreduced by the turbulent flow generated by the protrusion portion 30. Asa result, it is possible to more reliably improve fuel economyperformance.

Further, the position of the maximum height portion Hm in the tireradial direction is included within a range of no less than 0.40 and nomore than 0.60 times the tire cross-sectional height SH. Thus, theprotrusion portion 30 can locate the generation position of turbulentflow at the position near the center of the tire cross-sectional heightSH in the tire radial direction. With this, the rolling resistance canbe reduced more reliably. In other words, the position of the maximumheight portion Hm in the tire radial direction is at a position lessthan 0.40 times the tire cross-sectional height SH, the position of themaximum height portion Hm in the tire radial direction may beexcessively inward in the tire radial direction. Turbulent flowgenerated at the protrusion portion 30 is generated mostly near themaximum height portion Hm. Thus, when the position of the maximum heightportion Hm in the tire radial direction is excessively inward in thetire radial direction, the generation position of turbulent flow may beexcessively inward in the tire radial direction. In this case, it isdifficult to effectively suppress the increase in air resistance due toturbulent flow when the pneumatic tire 1 rotates, which may make itdifficult to reduce the rolling resistance. Further, when the positionof the maximum height portion Hm in the tire radial direction is at aposition exceeding 0.60 times the tire cross-sectional height SH, theposition of the maximum height portion Hm in the tire radial directionmay be excessively outward in the tire radial direction. In this case,the generation position of turbulent flow may be excessively outward inthe tire radial direction. Thus, it is difficult to effectively suppressthe increase in air resistance due to turbulent flow when the pneumatictire 1 rotates, which may make it difficult to reduce the rollingresistance.

In view of this, the position of the maximum height portion Hm of theprotrusion portion 30 in the tire radial direction is included within arange of no less than 0.40 and no more than 0.60 times the tirecross-sectional height SH, the position of the maximum height portion Hmin the tire radial direction can be located near the center of the tirecross-sectional height SH in the tire radial direction. Thus, thegeneration position of turbulent flow can be generated near the centerof the tire cross-sectional height SH in the tire radial direction. Inthis way, an increase in air resistance when the pneumatic tire 1rotates may be effectively suppressed by turbulent flow generated at theprotrusion portion 30, and the rolling resistance may be reduced morereliably. As a result, it is possible to more reliably improve fueleconomy performance.

Further, the position of the maximum width portion Wm in the tire radialdirection is included within a range of no less than 0.40 and no morethan 0.60 times the tire cross-sectional height SH. Thus, the protrusionportion 30 can locate the generation position of turbulent flow at theposition near the center of the tire cross-sectional height SH in thetire radial direction. With this, the rolling resistance can be reducedmore reliably. In other words, the position of the maximum width portionWm in the tire radial direction is at a position less than 0.40 timesthe tire cross-sectional height SH, the position of the maximum widthportion Wm in the tire radial direction may be excessively inward in thetire radial direction. Turbulent flow generated at the protrusionportion 30 is generated mostly near the maximum width portion Wm. Thus,when the position of the maximum width portion Wm in the tire radialdirection is excessively inward in the tire radial direction, thegeneration position of turbulent flow may be excessively inward in thetire radial direction. In this case, it is difficult to effectivelysuppress the increase in air resistance due to turbulent flow when thepneumatic tire 1 rotates, which may make it difficult to reduce therolling resistance. Further, when the position of the maximum widthportion Wm in the tire radial direction is a position exceeding 0.60times the tire cross-sectional height SH, the position of the maximumwidth portion Wm in the tire radial direction may be excessively outwardin the tire radial direction. In this case, the generation position ofturbulent flow may be excessively outward in the tire radial direction.Thus, it is difficult to effectively suppress the increase in airresistance due to turbulent flow when the pneumatic tire 1 rotates,which may make it difficult to reduce the rolling resistance.

In view of this, when the position of the maximum width portion Wm ofthe protrusion portion 30 in the tire radial direction is includedwithin a range of no less than 0.40 and no more than 0.60 times the tirecross-sectional height SH, the position of the maximum width portion Wmin the tire radial direction can be located near the center of the tirecross-sectional height SH in the tire radial direction. Thus, thegeneration position of turbulent flow can be generated near the centerof the tire cross-sectional height SH in the tire radial direction. Inthis way, an increase in air resistance when the pneumatic tire 1rotates may be effectively suppressed by turbulent flow generated at theprotrusion portion 30, and the rolling resistance may be reduced morereliably. As a result, it is possible to more reliably improve fueleconomy performance.

Additionally, the protrusion portion 30 has a plurality of bent portions40. Thus, turbulent flow is more likely to be generated at the positionof the bent portion 40, and hence turbulent flow can be generated morereliably. In this way, an increase in air resistance when the pneumatictire 1 rotates may be effectively suppressed by turbulent flow, and therolling resistance may be reduced more reliably. Further, the protrusionportion 30 includes the bent portion 40 at at least one position. Withthis, the length of the protrusion portion 30 can be increased. Also,the direction in which the protrusion portion 30 extends can be changedat the position of the bent portion 40. Thus, the protrusion portion 30can be easily brought into contact with an obstacle that is likely tocome into contact with the tire side surface 21. As a result, bothscratch resistance and fuel economy performance may be achieved morereliably in a compatible manner.

Further, the relative angle β in the tire circumferential directionbetween the two first extending portion end position lines Lerespectively passing through both the end portions 51 a of the firstextending portion 51 is within a range of 0.60≤(β/α)≤0.90 with respectto the angle α. Thus, the protrusion portion 30 can generate turbulentflow effectively with the first extending portion 51, and an effect ofgenerating turbulent flow, which is obtained by forming the bent portion40 in the protrusion portion 30, can be obtained effectively. In otherwords, when the angle β satisfies (β/α)≤0.60 with respect to the angleα, the arrangement region of the first extending portion 51 in the tirecircumferential direction is excessively small. Thus, even when the tireside portion 20 is provided with the protrusion portion 30, it may bedifficult to generate turbulent flow in the air around the protrusionportion 30. In other words, the first extending portion 51 is theextending portion 50 having the largest length among the plurality ofextending portions 50 of the protrusion portion 30. Thus, the firstextending portion 51 largely contributes to turbulent flow generated atthe protrusion portion 30. When the arrangement range of the firstextending portion 51 is small, and the length of the first extendingportion 51 is excessively short, it may be difficult to generateturbulent flow effectively. In this case, it is difficult to effectivelysuppress the increase in air resistance when the pneumatic tire 1 isrotated, which may make it difficult to reduce rolling resistance.

Further, when the angle β is (β/α)≤0.90 with respect to the angle α, thearrangement region of the first extending portion 51 in the tirecircumferential direction is excessively large, and the length of thefirst extending portion 51 is excessively long. Thus, it may bedifficult to effectively obtain an effect of generating turbulent flowby forming the bent portion 40 in the protrusion portion 30. In thiscase, it is also difficult to effectively suppress the increase in airresistance when the pneumatic tire 1 rotates, which may make itdifficult to reduce the rolling resistance.

In view of this, when the angle β is within a range of 0.60≤(β/α)≤0.90with respect to the angle α, the protrusion portion 30 can generateturbulent flow effectively with the first extending portion 51, and aneffect of generating turbulent flow, which is obtained by forming thebent portion 40 in the protrusion portion 30, can be obtainedeffectively. Accordingly, an increase in air resistance when thepneumatic tire 1 rotates can be more reliably suppressed, and therolling resistance can be more reliably reduced. As a result, it ispossible to more reliably improve fuel economy performance.

In addition, the protrusion portions 30 are such that the angle θ1formed by the center line 51 c of the first extending portion 51 in thewidth direction and the center line 52 c in the width direction of thesecond extending portion 52 is within the range 90°≤θ1≤170°, so it ispossible to more reliably reduce rolling resistance while suppressingthe occurrence of cracks at the positions of the bend portions 40. Inother words, in a case where the angle θ1 is less than 90°, the angleformed by the first extending portion 51 and the second extendingportion 52 is too small, so there is a possibility that when the vehicleis traveling, the tire side portion 20 may bend or the like, making iteasy for stress concentration to occur near the position of the bendportion 40. In this case, there is a risk that cracking may easily occurat the position of the bend portion 40. Furthermore, in a case where theangle θ1 exceeds 170°, the angle formed by the first extending portion51 and the second extending portion 52 is too large, so it is difficultto effectively obtain the effect of generating turbulent flow by forminga bend portion 40 in the protrusion portion 30. In this case, it isdifficult to effectively suppress the increase in air resistance whenthe pneumatic tire 1 is rotated, which may make it difficult to reducerolling resistance.

On the other hand, in a case where the angle θ1 is within the range90°≤θ1≤170°, the effect of generating a turbulent flow by forming thebend portion 40 in the protrusion portion 30 may be effectively obtainedwhile suppressing the occurrence of cracking at the position of the bendportion 40, and rolling resistance may be more reliably reduced. As aresult, it is possible to more reliably improve fuel economy performancewhile suppressing damage to the tire side portion 20.

Further, the inclination directions of the plurality of first extendingportions 51 of the plurality of protrusion portions 30, which are in thetire radial direction with respect to the tire circumferentialdirection, are all the same direction. Thus, when turbulent flow isgenerated at the first extending portion 51 that largely contributes togeneration of turbulent flow at the protrusion portion 30, turbulentflow can be generated more effectively by the plurality of firstextending portions 51. Accordingly, an increase in air resistance whenthe pneumatic tire 1 rotates can be more reliably suppressed, and therolling resistance can be more reliably reduced. As a result, it ispossible to more reliably improve fuel economy performance.

Further, the first extending portion 51 is inclined with respect to thetire circumferential direction in a direction from the inner side to theouter side in the tire radial direction while going from the leadingside to the trailing side in the rotation direction of the pneumatictire 1. Thus, a force of pressing down the pneumatic tire 1 on a roadsurface can be improved. In other words, the inclination direction ofthe first extending portion 51 is inclined in the direction from theinner side to the outer side in the tire radial direction while goingfrom the leading side to the trailing side in the rotation direction.With this, the air flowing near the tire side surface 21 when thepneumatic tire 1 rotates is caused to change a flow direction in thedirection from the inner side to the outer side in the tire radialdirection due to the first extending portion 51. Here, when a vehiclemoves forward, a part of the pneumatic tire 1, which is positioned nearan upper end in a vertical direction, moves in a direction from a rearside to a front side of the vehicle. In contrast, a part of thepneumatic tire 1, which is positioned near a lower end in the verticaldirection, moves in a direction from the rear side to the front side ofthe vehicle. Thus, when a vehicle moves forward, a relative speed withrespect to a road surface is the fastest at the part of the pneumatictire 1, which is positioned near the upper end in the verticaldirection. Therefore, with regard to an impact on the pneumatic tire 1,which is caused by changing the flow direction of the air flowing nearthe tire side surface 21 due to the first extending portion 51, thefirst extending portion 51 positioned near the upper end of the verticaldirection of the pneumatic tire 1 has the largest impact on changing theair flow direction.

When the pneumatic tire 1 rotates, the first extending portion 51changes the direction of the air flowing near the tire side surface 21in the direction from the inner side to the outer side in the tireradial direction. Thus, the first extending portion 51 positioned nearthe upper end in the vertical direction of the pneumatic tire 1 changesthe air flow direction to the direction from the lower side to the upperside in the vertical direction. Thus, as a reaction caused by changingthe air flow, the first extending portion 51 receives a force ofpressing downward in the vertical direction from the air. The forcereceived by the first extending portion 51 from the air is a force ofpressing down the pneumatic tire 1 on a road surface. Thus, the forcepressing down on a road surface enables the pneumatic tire 1 to improvea gripping force of the ground contact surface 10 with respect to a roadsurface. As a result, the improved gripping force can improve steeringstability when the vehicle is traveling.

Further, the plurality of protrusion portions 30 include overlappingportions 55 that overlap different protrusion portions 30 in the tirecircumferential direction. Thus, the protrusion portions 30 can bearranged in a large range of the tire side surface 21 in the tirecircumferential direction. With this, the protrusion portion 30 can beeasily brought into contact with an obstacle that is likely to come intocontact with the tire side surface 21. As a result, scratch resistancemay be improved.

Further, in the protrusion portion 30, the angle γ in the tirecircumferential direction in the range in which the overlapping portion55 extends in the tire circumferential direction is within a range of0.05≤(γ/α)≤0.30 with respect to the angle α. Thus, an effect ofimproving scratch resistance can be obtained more reliably whilesuppressing an increase in weight of the protrusion portion 30. In otherwords, when the angle γ of the overlapping portion 55 is (γ/α)≤0.05 withrespect to the angle α, the length of the overlapping portion 55 in thetire circumferential direction is excessively short. Thus, even when theoverlapping portion 55 is provided, it may be difficult to improvescratch resistance effectively. Further, when the angle γ of theoverlapping portion 55 is (γ/α)>0.30 with respect to the angle α, thelength of the overlapping portion 55 in the tire circumferentialdirection is excessively long. Thus, the weight of the protrusionportion 30 may be excessively increased. In this case, the weight of thepneumatic tire 1 is increased along with an increase in weight of theprotrusion portion 30, which may degrade the rolling resistance.

In view of this, when the angle γ of the overlapping portion 55 iswithin a range of 0.05≤(γ/α)≤0.30 with respect to the angle α, anexcessive increase in weight of the protrusion portion 30 is suppressed.With this, an effect of improving scratch resistance, which is obtainedby providing the overlapping portion 55, can be achieved more reliablywhile suppressing degradation of the rolling resistance. As a result,both scratch resistance and fuel economy performance may be achievedmore reliably in a compatible manner.

Further, the relationship between the maximum distance Pmax and theminimum distance Pmin between the parts of the protrusion portions 30that overlap each other in the overlapping portion 55 in the tire radialdirection is within a range of 1.0≤(Pmax/Pmin)≤2.0. Thus, when theprotrusion portions 30 are provided, an effect of suppressing airresistance can be obtained more reliably. In other words, when therelationship between the maximum distance Pmax and the minimum distancePmin is (Pmax/Pmin)>2.0, the distance between the two protrusionportions 30 overlapping each other in the overlapping portion 55 ischanged excessively largely. Thus, turbulence may be newly generated inthe air flow passing through the protrusion portions 30. In this case,in addition to turbulent flow in the air, which is generated byproviding the protrusion portions 30, turbulent flow is newly generated.Thus, an effect of suppressing air resistance, which is obtained byproviding the protrusion portions 30, may be suppressed.

In view of this, when the relationship between the maximum distance Pmaxand the minimum distance Pmin is within a range of 1.0≤(Pmax/Pmin)≤2.0,the two protrusion portions 30 overlapping each other in the overlappingportion 55 can be close to a parallel state. An effect of suppressingair resistance, which is obtained by providing the protrusion portions30, can be obtained more reliably. As a result, it is possible to morereliably improve fuel economy performance.

Further, with regard to the protrusion portion 30, the minimum distancePmin between the two protrusion portions 30 overlapping each other inthe overlapping portion 55 is within a range of 0.15≤(Pmin/SH)≤0.30 withrespect to the tire cross-sectional height SH. Thus, the air passingthrough the two overlapping protrusion portions 30 can be rectified morereliably. In other words, the overlapping portion 55 has an effect ofrectifying the air and causing the air to flow in the tirecircumferential direction when the two protrusion portions 30 overlapeach other in a state close to a parallel state. With this, when the airis caused to flow in the tire circumferential direction and rectifiedwhile generating turbulent flow by the protrusion portion 30, airresistance can be suppressed more reliably.

However, when the minimum distance Pmin in the overlapping portion 55 is(Pmin/SH)≤0.15 with respect to the tire cross-sectional height SH, thedistance between the protrusion portions 30 is excessively narrow. Thus,the amount of the air passing through the two overlapping protrusionportions 30 in the overlapping portion 55 may be reduced. In this case,even when the overlapping portion 55 is provided, the amount of the airto be rectified is small. Thus, it may be difficult to obtain an effectof reducing air resistance, which is obtained by the overlapping portion55. Further, when the minimum distance Pmin in the overlapping portion55 is (Pmin/SH)>0.30 with respect to the tire cross-sectional height SH,the distance between the protrusion portions 30 is excessively wide.Thus, it may be difficult to rectify the air passing through the twooverlapping protrusion portions 30 in the overlapping portion 55. Also,in this case, it may be difficult to obtain an effect of reducing airresistance, which is obtained by the overlapping portion 55.

In view of this, when the minimum distance Pmin in the overlappingportion 55 is within a range of 0.15≤(Pmin/SH)≤0.30 with respect to thetire cross-sectional height SH, the air passing through the twooverlapping protrusion portions 30 can be rectified more reliably, andair resistance can be reduced by the overlapping portion 55 morereliably. As a result, it is possible to more reliably improve fueleconomy performance.

Further, the protrusion portions 30 overlap each other in theoverlapping portions 55, and hence one or more protrusion portions 30are arranged at any position on the tire circumference. Thus, at anyposition of the tire side surface 21 on the tire circumference, scratchresistance obtained by the protrusion portion 30 can be ensured.Further, one or more protrusion portions 30 are arranged at any positionon the tire circumference, and hence turbulent flow can be generated bythe protrusion portion 30 at any position of the tire side surface 21 onthe tire circumference, and air resistance can be reduced more reliably.As a result, both scratch resistance and fuel economy performance may beachieved more reliably in a compatible manner.

Further, with regard to the protrusion portion 30, the sum of the anglesα of the plurality of protrusion portions 30 formed on one tire sideportion 20 is within a range of no less than 105% and no more than 200%of the angle 2π of one round in the tire circumferential direction.Thus, an excessive increase in total weight of the protrusion portions30 can be suppressed while ensuring scratch resistance by the protrusionportions 30 at a larger number of positions on the tire circumference.In other words, when the sum of the angles α of the plurality ofprotrusion portions 30 is less than 105% of the angle 2π of one round inthe tire circumferential direction, the sum of the angles α of theprotrusion portions 30 is excessively small. Thus, in accordance withthe shape or the arrangement configuration of the protrusion portions30, a part in which it is difficult for the protrusion portion 30 toensure scratch resistance may be generated on the tire circumference.Further, when the sum of the angles α of the plurality of protrusionportions 30 exceeds 200% of the angle 2π of one round in the tirecircumferential direction, the sum of the angles α of the protrusionportions 30 is excessively large. Thus, the total weight of theprotrusion portions 30 may be excessively increased. In this case, theweight of the pneumatic tire 1 is increased along with an increase intotal weight of the protrusion portions 30, which may degrade therolling resistance.

In view of this, when the sum of the angles α of the plurality ofprotrusion portions 30 is within a range of no less than 105% and nomore than 200% of the angle 2π of one round in the tire circumferentialdirection, an excessive increase in total weight of the protrusionportions 30 can be suppressed while ensuring scratch resistance by theprotrusion portions 30 at a larger number of positions on the tirecircumference. With this, degradation of the rolling resistance can besuppressed. As a result, both scratch resistance and fuel economyperformance may be achieved more reliably in a compatible manner.

Further, the protrusion portions 30 are formed on one tire side portion20 within a range of no less than 2 and no more than 16. Thus, anincrease in air resistance when the pneumatic tire 1 rotates can besuppressed more reliably while suppressing generation of a crack.Further, scratch resistance can be ensured by the protrusion portions 30at a larger number of positions on the tire circumference. In otherwords, when the number of protrusion portions 30 formed on one tire sideportion 20 is less than two, the number of the protrusion portions 30 isexcessively small. Thus, turbulent flow generated by the protrusionportion 30 may be excessively small. In this case, it may be difficultfor turbulent flow to suppress an increase in air resistance when thepneumatic tire 1 rotates and to reduce the rolling resistance. Further,when the number of protrusion portions 30 formed on one tire sideportion 20 is less than two, the number of protrusion portions 30 isexcessively small. Thus, in accordance with the shape or the arrangementconfiguration of the protrusion portions 30, a part in which it isdifficult for the protrusion portion 30 to ensure scratch resistance maybe generated on the tire circumference. Further, when the number ofprotrusion portions 30 formed on one tire side portion 20 is more thansixteen, the number of protrusion portions 30 is excessively large.Thus, a crack may be likely to be generated. In other words, theprotrusion portion 30 is formed in such a way to protrude from the tireside surface 21, and hence is a part on which stress concentration islikely to occur. However, when the number of protrusion portions 30 isexcessively large, the number of parts on which a stress is likely toconcentrate is increased, and thus a crack may be likely to begenerated.

In view of this, when no less than two and no more than sixteen of theprotrusion portions 30 are formed on one tire side portion 20, anincrease in air resistance when the pneumatic tire 1 rotates can besuppressed more reliably by turbulent flow generated at the protrusionportion 30 while suppressing generation of a crack. Further, scratchresistance can be ensured by the protrusion portions 30 at a largernumber of positions on the tire circumference. As a result, both scratchresistance and fuel economy performance may be achieved more reliably ina compatible manner while suppressing damage to the tire side portion20.

Additionally, the protrusion portions 30 are formed on the tire sideportion 20 on the outer side in the vehicle mounting direction, soscratch resistance and fuel economy performance may be more effectivelyimproved. In other words, the tire side surface 21 on the outer side inthe vehicle mounting direction is a portion that constitutes theappearance of the vehicle, so it becomes easy to come in contact with anobstacle such as a curb or the like. Thus, by forming the protrusionportions 30 on the tire side surface 21 on the outer side in the vehiclemounting direction, the tire side surface 21 on the outer side in thevehicle mounting direction, which is prone to contact an obstacle suchas curb, may be more reliably protected by the protrusion portions 30.Furthermore, the tire side surface 21 on the outer side in the vehiclemounting direction faces the outer side of the vehicle over the entiresurface, making it easier to receive a direct flow of air duringtraveling of the vehicle. Accordingly, by forming the protrusionportions 30 on the tire side surface 21 on the outer side in the vehiclemounting direction, turbulent flow may be effectively generated at aposition where the flow of air during traveling of the vehicle is easilyreceived, increases in the air resistance when the pneumatic tire 1 isrotated may be effectively suppressed, and rolling resistance may bemore reliably reduced. As a result, both scratch resistance and fueleconomy performance may be more reliably achieved in a compatiblemanner.

Modified Examples

Note that in the pneumatic tire 1 according to the embodiment describedabove, two bend portions 40 are formed on one protrusion portion 30, buttwo or more bend portions 40 may be formed. FIG. 16 is a modifiedexample of a pneumatic tire 1 according to an embodiment, and is anexplanatory diagram of a case where there is one bend portion 40 in theprotrusion portion 30. FIG. 17 is a modified example of a pneumatic tire1 according to an embodiment, and is an explanatory diagram of a casewhere there are three bend portions 40 in the protrusion portion 30. Thebend portions 40 formed on one protrusion portion 30 may be, forexample, one as illustrated in FIG. 16, or may be three as illustratedin FIG. 17. In other words, in the protrusion portion 30, as illustratedin FIG. 16, the extending portions 50 formed by the bend portion 40 maybe defined into two extending portions by one bend portion 40: a firstextending portion 51 and a second extending portion 52; or asillustrated in FIG. 17, may be defined into four extending portions bythree bend portions 40: a first extending portion 51, a second extendingportion 52, a third extending portion 53, and a fourth extending portion54. Regardless of the number of bend portions 40, by the bend portions40 being formed, the protrusion portion 30 can easily generate turbulentflow at the position of the bend portions 40. In this way, an increasein air resistance when the pneumatic tire 1 is rotated may beeffectively suppressed by the turbulent flow, rolling resistance may bemore reliably reduced, and fuel economy performance may be improved.

In the pneumatic tire 1 according to the embodiment described above, thefirst extending portion 51 having the longest length of the plurality ofextending portions 50 of one protrusion portion 30 is positioned on theoutermost side in the tire radial direction; however, the firstextending portion 51 does not have to be positioned on the outermostside in the tire radial direction. FIG. 18 is a modified example of apneumatic tire 1 according to an embodiment, and is an explanatorydiagram of a case in which the first extending portion 51 is positionedfurther toward the inner side in the tire radial direction than thesecond extending portion 52. The extending portions 50 formed on oneprotrusion portion 30 may be such that, as illustrated in FIG. 18, forexample, the first extending portion 51, which is the extending portion50 having the longest length of the plurality of extending portions 50,is positioned further on the inner side in the tire radial directionthan the second extending portion 52. The protrusion portion 30 isformed in such a way that the arrangement range of the first extendingportion 51 in the tire circumferential direction is within a range of noless than 6% and no more than 50% of the angle 2π of one round in thetire circumferential direction, regardless of the position of the firstextending portion 51 in the tire radial direction. With this, theprotrusion portion 30 can be easily brought into contact with anobstacle that is likely to come into contact with the tire side surface21 while suppressing an increase in weight. Further, the protrusionportion 30 can effectively generate turbulent flow. Accordingly, scratchresistance and fuel consumption performance can be achieved in acompatible manner.

Additionally, in the pneumatic tire 1 according to the embodimentdescribed above, the second extending portion 52, which is the highestextending portion 56 of the plurality of extending portions 50, has thehighest average extending portion height, and the first extendingportion 51 and the third extending portion 53 have an average extendingportion height that is lower than that of the second extending portion52; however, even in a case where there are three or more bend portions40 formed on one protrusion portion 30, it is preferable that an averageextending portion height decreases as the extending portions 50 moveaway from the highest extending portion 56. FIG. 19 is a modifiedexample of a pneumatic tire 1 according to an embodiment, and is anexplanatory diagram of an average extending portion height of aplurality of extending portions 50 of a protrusion portion 30 includingfour bend portions 40. In a case where, for example, four bend portions40 are formed in one protrusion portion 30 and five extending portions50 are defined by the bend portions 40, as illustrated in FIG. 19,preferably the average extending portion height of the extendingportions 50 other than the highest extending portion 56 becomes lowergoing away from the highest extending portion 56 in a case where thehighest extending portion 56 is the extending portion 50 located at thecenter among the five extending portions 50 in the direction in whichthe extending portions 50 are arranged.

More specifically, in the protrusion portion 30 illustrated in FIG. 19,by the extending portion 50 located at the center in the direction inwhich the extending portions 50 are arranged having a maximum heightportion Hm which is a portion having the highest height in theprotrusion portion 30, that extending portion 50 is provided as thehighest extending portion 56. Moreover, of the plurality of extendingportions 50, the extending portion 50 that is continuous from thehighest extending portion 56 via the bend portion 40 is provided as anadjacent extending portion 57, and the adjacent extending portion 57 hasan average extending portion height that is lower than an averageextending portion height of the highest extending portion 56.Furthermore, in the protrusion portion 30 illustrated in FIG. 19, of theplurality of extending portions 50, the extending portion 50 positionedon the opposite side to the side where the highest extending portion 56is located as seen from the adjacent extending portion 57 has an averageextending portion height that is lower than or equal to an averageextending portion height of the adjacent extending portion 57. In otherwords, the protrusion portion 30 is such that the plurality of extendingportions 50 from the adjacent extending portion 57 to the extendingportion 50 located at the end in the extending direction of theprotrusion portion 30 have an average extending portion height that islower than or equal to the average extending portion height of theadjacent extending portion 57.

The protrusion portion 30 is such that by the height becoming lowergoing away from the highest extending portion 56 in the extendingdirection of the protrusion portion 30, it is possible to suppress anexcessive increase in air resistance due to the provision of theprotrusion portion 30 by making the change in height from the tire sidesurface 21 as gentle as possible, while at the same time generateturbulent flow by the protrusion portion 30. Accordingly, an increase inair resistance when the pneumatic tire 1 rotates can be more reliablysuppressed, and the rolling resistance can be more reliably reduced. Asa result, it is possible to more reliably improve fuel economyperformance.

As described above, the protrusion portion 30 is such that regardless ofthe number of bend portions 40 preferably the height Hc of the extendingportion 50 located further on the outer side in the tire radialdirection from at least the highest extending portion 56 is lower thanthe height Hc of the highest extending portion 56, and more preferablythe height Hc of the extending portion 50 located further on the innerside in the tire radial direction than the highest extending portion 56is also lower than the height Hc of the highest extending portion 56. Inthis case, the height Hc of the protrusion portion 30 decreasesgradually from the maximum height Hm toward the outer side in the tireradial direction or from the maximum height Hm toward the inner side inthe tire radial direction.

Furthermore, the width Wc of the protrusion portion 30 is such that inthe extending portion 50 among the plurality of extending portions 50having the maximum width portion Wm of the protrusion portion 30, apredetermined range in the extending portion 50, or the entire range ofthe extending portion 50 may be formed having a width Wc of the maximumwidth portion Wm. Moreover, the protrusion portion 30 is such in theextending portion 50 of the plurality of extending portions 50 that isfurther on the outer side in the tire radial direction from theextending portion 50 having the maximum width portion Wm of theprotrusion portion 30, the width Wc is preferably narrower than thewidth Wc of the extending portion 50 having the maximum width portionWm, and in the extending portion 50 further on the inner side in thetire radial direction than the extending portion 50 having the maximumwidth Wm, the width Wc is also preferably narrower than the width Wc ofthe extending portion 50 having the maximum width portion Wm.

In the pneumatic tire 1 according to the embodiment described above, thecross-sectional shape of the protrusion portion 30 when viewed in theextending direction of the protrusion portion 30 is formed having asubstantially rectangular shape in which the height direction of theprotrusion portion 30 is the longitudinal direction; however, theprotrusion portion 30 may have a shape other than that. FIG. 20 is amodified example of a pneumatic tire 1 according to an embodiment, andis an explanatory diagram of a case in which the cross-sectional shapeof the protrusion portion 30 is formed into a rectangular shape having alateral length. FIG. 21 is a modified example of a pneumatic tire 1according to an embodiment, and is an explanatory diagram of a case inwhich the cross-sectional shape of the protrusion portion 30 is formedinto a trapezoidal shape. FIG. 22 is a modified example of a pneumatictire 1 according to an embodiment, and is an explanatory diagram of acase in which the cross-sectional shape of the protrusion portion 30 isformed into a triangular shape. The protrusion portion 30 may be, asillustrated in FIG. 20, for example, formed such that thecross-sectional shape when viewed in the extending direction of theprotrusion portion 30 is a substantially rectangular shape in which thewidth direction of the protrusion portion 30 is the longitudinaldirection. Moreover, the protrusion portion 30 is such that the widthmay change depending on the position in the height direction from thetire side surface 21, so the cross-sectional shape of the protrusionportion 30, as illustrated in FIG. 21 for example, may be formed in asubstantially trapezoidal shape, the width of which narrows going awayfrom the tire side surface 21, or as illustrated in FIG. 22, may beformed in a triangular shape.

As described above, the cross-sectional shape of the protrusion portion30 may be any shape that can project from the tire side surface 21 andgenerate turbulent flow. Additionally, the protrusion portion 30 doesnot have to have the same shape depending on the position of theprotrusion portion 30 in the extending direction, and thecross-sectional shape may vary depending on the position in theextending direction of the protrusion portion 30.

FIG. 23 is a modified example of a pneumatic tire 1 according to anembodiment, and is an explanatory diagram of a case in which arcportions 35 are formed at the base of the protrusion portion 30.Moreover, in a case where an arc portion 35 as illustrated in FIG. 23 isformed in a portion of the protrusion portion 30 connected to the tireside surface 21, or in other words, in a base portion of the protrusionportion 30, for the purpose of reducing stress concentration andconvenience of manufacturing, the width Wc of the protrusion portion 30is preferably a width including the arc portion 35. By defining a widthof the protrusion portion 30 including the arc portion 35 as the widthWc of the protrusion portion 30, the shape of the protrusion portion 30may be made more appropriate in consideration of reduction of stressconcentration and convenience in manufacturing.

Additionally, in the pneumatic tire 1 according to the embodimentdescribed above, the protrusion portion 30 may be formed on the tireside portion 20 on the outer side in the vehicle mounting direction;however, the protrusion portion 30 may also be formed on the tire sideportion 20 on the inner side in the vehicle mounting direction, or inother words, the protrusion portion 30 may also be formed on the tireside surface 21 of the tire side portion 20 on both sides in the tirewidth direction. By forming the protrusion portion 30 on the tire sidesurface 21 on both sides in the tire width direction, the tire sidesurface 21 on both sides in the tire width direction can may beprotected by the protrusion portion 30, and an increase in airresistance during rotation of the pneumatic tire 1 may be suppressed bythe tire side surface 21 on both sides in the tire width direction, andthus rolling resistance may be reduced more reliably. As a result,scratch resistance and fuel consumption performance can be achieved in amore compatible manner.

Furthermore, the protrusion portion 30 may be formed only on the tireside surface 21 on the inner side in the vehicle mounting direction. Thetire side surface 21 on the inner side in the vehicle mounting directiondoes not face the outer side of the vehicle, so it is difficult to seefrom the outside of the vehicle. Therefore, when the protrusion portion30 is formed on the tire side surface 21 on the inner side in thevehicle mounting direction, the protrusion portion 30 is also difficultto see. As a result, by forming the protrusion portion 30 on the tireside surface 21 on the inner side in the vehicle mounting direction,scratch resistance and fuel consumption performance can be achieved in acompatible manner without affecting the appearance of the vehicle.

As described above, a secondary effect obtained differs depending on thetire side portion 20 provided with the protrusion portion 30, so theprotrusion portion 30 may be formed on at least one tire side portion ofthe tire side portions 20 located on both sides in the tire widthdirection, depending on the usage of the pneumatic tire 1 and thevehicle.

Moreover, in the pneumatic tire 1 according to the embodiment describedabove, an imaginary circle Vc (see FIG. 8) used to obtain the angle θnformed by the center lines of two continuous extending portions 50 viathe bend portion 40, or an imaginary circle Vc used when comparing theinclinations of the extending portions 50 (see FIG. 9), or an imaginarycircle Vp used to specify that the first extending portion 51 and thethird extending portion 53 are substantially parallel (see FIG. 13) aresuch that of the extending portions 50 compared, the radius is half thelength of the extending portion 50 on the shorter side; however, theimaginary circle Vc and the imaginary circle Vp may have other sizes. Asthe imaginary circle Vc and the imaginary circle Vp, it is possible touse a circle having a preset radius, for example, a circle having aradius of 10 mm may be used. As the imaginary circle Vc and theimaginary circle Vp, preferably an appropriate circle according to thesize and shape of the protrusion portion 30 is used.

Furthermore, in the pneumatic tire 1 according to the above-describedembodiment, the plurality of protrusion portions 30 and the firstextending portions 51 formed on one tire side surface 21 all have thesame inclination direction in the tire radial direction when going in apredetermined direction in the tire circumferential direction; howeverthe inclination directions of the protrusion portions 30 and the firstextending portions 51 need not be the same. For example, a plurality ofprotrusion portions 30 formed on one tire side surface 21 may be suchthat the inclination directions in the tire radial direction when goingin a predetermined direction in the tire circumferential direction maybe in opposite directions to each other for protrusion portions 30adjacent to each other in the tire circumferential direction. In otherwords, a plurality of protrusion portions 30 formed on one tire sidesurface 21 may be such that by making the inclination directions of theprotrusion portions 30 adjacent to each other in the tirecircumferential direction opposite to each other, the protrusionportions 30 adjacent to each other in the tire circumferential directionare disposed in a V shape. By making the inclination directions of theprotrusion portions 30 in the tire radial direction with respect to thetire circumferential direction opposite to each other, the protrusionportions 30 appropriately generate turbulence regardless of whichdirection the pneumatic tire 1 rotates, and it is possible to suppressan increase in air resistance and reduce the rolling resistance. In thisway, fuel economy performance may be improved regardless of the rotationdirection of the pneumatic tire 1.

EXAMPLES

FIGS. 24A to 24F are tables listing the results of performance tests ofpneumatic tires. Hereinafter, performance evaluation tests of thepneumatic tire 1 described above with respect to the conventionalpneumatic tire and the pneumatic tire 1 according to the presenttechnology will be described. Performance evaluation tests wereperformed in order to test for fuel economy performance and for scratchresistance.

The performance evaluation tests were performed by mounting a pneumatictire 1 with a tire nominal size of 205/55R16 specified by JATMA on aJATMA standard rim wheel with a rim size of 16×6.5 J, adjusting the airpressure to 230 kPa, mounting the test tire on the evaluation vehiclewith an engine displacement of 2000 cc, and then driving the evaluationvehicle.

Regarding the evaluation method of each test item, an evaluation vehicleequipped with test tires was subjected to a test run of 50 laps on atest course having a total length of 2 km at 100 km/h, and the fuelconsumption due to the test run was measured. The fuel economyperformance is indicated by an index in which the reciprocal of themeasured fuel consumption is set to 100 in Conventional Exampledescribed later. The larger this value is, the smaller the fuelconsumption is and the better the fuel economy performance is.

Moreover, regarding scratch resistance, in an evaluation vehicleequipped with test tires, the tires were made to collide with a curbwith a height of 100 mm at an approach angle of 45° and an approachspeed of 10 km/h, the approach speed was gradually increased from 10km/h, and the approach speed at which the tire burst was measured. Thescratch resistance is indicated by an index of the approach speedleading to the burst, with the Conventional Example described laterbeing set as 100. The larger this value is, the less likely it is thatbursts will occur, indicating that the scratch resistance is excellent.

The performance evaluation test was carried out on 24 types of pneumatictires, or in other words, the pneumatic tires of Conventional Examplewhich was an example of a conventional pneumatic tire, and Examples 1 to23, which were the pneumatic tires 1 according to the presenttechnology. Among those, the conventional pneumatic tire had theprotrusion portions 30 formed on the tire side portion 20, but therelative angle α in the tire circumferential direction between the twoprotrusion portion end position lines Lc respectively passing throughboth the end portions 31 of the protrusion portion 30 was less than 6%of the angle 2π of one round in the tire circumferential direction.

In view of this, in each of all the Examples 1 to 23 being examples ofthe pneumatic tire 1 according to the present technology, the relativeangle α in the tire circumferential direction between the two protrusionportion end position lines Lc respectively passing through both the endportions 31 of the protrusion portion 30 was within a range of no lessthan 6% and no more than 50% of the angle 2π of one round in the tirecircumferential direction. Further, the pneumatic tires 1 according toexamples 1 to 23 were different from one another in the distanceDmax/the distance Dmin, the distance Dmax/the tire cross-sectionalheight SH, the position of the maximum height portion Hm with respect tothe tire cross-sectional height SH, the number of bent portions 40 ofthe protrusion portion 30, the angle β/the angle α, the angle θ1 formedbetween the first extending portion 51 and the second extending portion52, presence or absence of the overlapping portion 55, a ratio of theprotrusion portions 30 including the overlapping portion 55, the angleγ/the angle α, the maximum distance Pmax/the minimum distance Pmin, theminimum distance Pmin/the tire cross-sectional height SH, the sum of theangles α/the angle 2π of one round in the tire circumferentialdirection, the number of protrusion portions 30, the inclinationdirection of the plurality of first extending portions 51, theinclination direction of the first extending portion 51 in the tireradial direction while going from the leading side to the trailing sidein the rotation direction of the pneumatic tire 1, and the like.

As a result of performing performance evaluation tests using thesepneumatic tires 1, as illustrated in FIGS. 24A to 24F, the pneumatictires 1 according to Examples 1 to 23 were able to improve both fueleconomy performance and scratch resistance as compared to that inConventional Example. In other words, the pneumatic tires 1 according toExamples 1 to 23 have both scratch resistance and fuel economyperformance in a compatible manner.

1. A pneumatic tire, comprising: a plurality of protrusion portionsformed on at least one tire side portion of tire side portions locatedon both sides in a tire width direction, the protrusion portionsprojecting from a tire side surface that is a surface of the tire sideportion and extending along the tire side surface, the protrusionportions having an angle α within a range of no less than 6% and no morethan 50% of an angle of one round in a tire circumferential direction,the angle α being relative and in the tire circumferential directionbetween two protrusion portion end position lines that respectivelyextend in a tire radial direction through different end portions of bothend portions in an extending direction of the protrusion portions, andthe tire side portion having a thickness at a tire maximum widthposition within a range of no less than 2 mm and no more than 9 mm. 2.The pneumatic tire according to claim 1, wherein the protrusion portionshave a distance Dmax and a distance Dmin, the distance Dmax being adistance in a tire radial direction between a tire outer diameterportion and an innermost portion of the protrusion portions in the tireradial direction, the distance Dmin being a distance in the tire radialdirection between the tire outer diameter portion and an outermostportion of the protrusion portions in the tire radial direction, and arelationship between the distance Dmax and the distance Dmin is within arange of 1.2≤(Dmax/Dmin)≤3.5.
 3. The pneumatic tire according to claim2, wherein the distance Dmax is within a range of no less than 0.30 andno more than 0.70 times a tire cross-sectional height.
 4. The pneumatictire according to claim 1, wherein the protrusion portions are formedacross the tire maximum width position on the tire side surface in thetire radial direction.
 5. The pneumatic tire according to claim 1,wherein in the protrusion portions, a position of a portion in the tireradial direction where a height from the tire side surface is highest,is included within a range of no less than 0.40 and no more than 0.60times a tire cross-sectional height.
 6. The pneumatic tire according toclaim 1, wherein in the protrusion portions, a position of a maximumwidth portion in the tire radial direction is included within a range ofno less than 0.40 and no more than 0.60 times a tire cross-sectionalheight.
 7. The pneumatic tire according to claim 1, wherein theprotrusion portions comprise at least one bent portion at a positionwhere a direction in which the protrusion portions extend changes. 8.The pneumatic tire according to claim 7, wherein the protrusion portionscomprise a plurality of extending portions defined by the at least onebent portion, and a first extending portion, which is the extendingportion having a longest length among the plurality of extendingportions, has an angle β within a range of 0.60≤(β/α)≤0.90 with respectto the angle α, the angle β being relative and in the tirecircumferential direction between two first extending portion endposition lines that respectively extend in the tire radial directionthrough different end portions of both end portions in the extendingdirection of the first extending portion.
 9. The pneumatic tireaccording to claim 8, wherein the protrusion portions have an angle θ1,the angle θ1 being formed between a center line in a width direction ofthe first extending portion and a center line in a width direction of asecond extending portion, the second extending portion being theextending portion continuous from the first extending portion via the atleast one bent portion, and the angle θ1 is within a range of90°≤θ1≤170°.
 10. The pneumatic tire according to claim 8, wherein theplurality of extending portions of the plurality of protrusion portionshave a same direction of inclination in the tire radial direction withrespect to the tire circumferential direction.
 11. The pneumatic tireaccording to claim 8, wherein when a vehicle moves forward, thepneumatic tire is mounted on the vehicle in such a way that thepneumatic tire rotates about a rotation direction that is designated,and the first extending portion is inclined in a direction from an innerside to an outer side in the tire radial direction with respect to thetire circumferential direction while going from a leading side to atrailing side in the rotation direction.
 12. The pneumatic tireaccording to claim 1, wherein the protrusion portions comprise anoverlapping portion that is a portion where different protrusionportions overlap in the tire circumferential direction.
 13. Thepneumatic tire according to claim 12, wherein the protrusion portionshave an angle γ within a range of 0.05≤(γ/α)≤0.30 with respect to theangle α, the angle γ being in the tire circumferential direction in arange where the overlapping portion extends in the tire circumferentialdirection.
 14. The pneumatic tire according to claim 12, wherein two ofthe protrusion portions overlapping each other in the overlappingportion have a maximum distance Pmax and a minimum distance Pmin in atire radial direction between the overlapping portions, and arelationship between the maximum distance Pmax and the minimum distancePmin is within a range of 1.0≤(Pmax/Pmin)≤2.0.
 15. The pneumatic tireaccording to claim 14, wherein the minimum distance Pmin is within arange of 0.15≤(Pmin/SH)≤0.30 with respect to a tire cross-sectionalheight SH.
 16. The pneumatic tire according to claim 12, wherein theprotrusion portions overlap in the overlapping portion, and one or moreof the protrusion portions are arranged at any position on a tirecircumference.
 17. The pneumatic tire according to claim 1, wherein asum of the angles α of the protrusion portions formed on one tire sideportion is within a range of no less than 105% and no more than 200% ofthe angle of one round in the tire circumferential direction.
 18. Thepneumatic tire according to claim 1, wherein the protrusion portions areformed on one tire side portion within a range of no less than twoprotrusion portions and no more than sixteen protrusion portions.